diff --git a/src/sagemaker/jumpstart/artifacts/environment_variables.py b/src/sagemaker/jumpstart/artifacts/environment_variables.py
index 006559852c..fa5ae8900b 100644
--- a/src/sagemaker/jumpstart/artifacts/environment_variables.py
+++ b/src/sagemaker/jumpstart/artifacts/environment_variables.py
@@ -15,7 +15,6 @@
 from typing import Callable, Dict, Optional, Set
 from sagemaker.jumpstart.constants import (
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
-    JUMPSTART_DEFAULT_REGION_NAME,
     JUMPSTART_LOGGER,
     SAGEMAKER_GATED_MODEL_S3_URI_TRAINING_ENV_VAR_KEY,
 )
@@ -24,6 +23,7 @@
 )
 from sagemaker.jumpstart.utils import (
     get_jumpstart_gated_content_bucket,
+    get_region_fallback,
     verify_model_region_and_return_specs,
 )
 from sagemaker.session import Session
@@ -72,8 +72,9 @@ def _retrieve_default_environment_variables(
         dict: the inference environment variables to use for the model.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
@@ -198,8 +199,9 @@ def _retrieve_gated_model_uri_env_var_value(
         ValueError: If the model specs specified are invalid.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
diff --git a/src/sagemaker/jumpstart/artifacts/hyperparameters.py b/src/sagemaker/jumpstart/artifacts/hyperparameters.py
index e9e6f613f8..d19530ecfb 100644
--- a/src/sagemaker/jumpstart/artifacts/hyperparameters.py
+++ b/src/sagemaker/jumpstart/artifacts/hyperparameters.py
@@ -15,13 +15,13 @@
 from typing import Dict, Optional
 from sagemaker.jumpstart.constants import (
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
-    JUMPSTART_DEFAULT_REGION_NAME,
 )
 from sagemaker.jumpstart.enums import (
     JumpStartScriptScope,
     VariableScope,
 )
 from sagemaker.jumpstart.utils import (
+    get_region_fallback,
     verify_model_region_and_return_specs,
 )
 from sagemaker.session import Session
@@ -70,8 +70,9 @@ def _retrieve_default_hyperparameters(
         dict: the hyperparameters to use for the model.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
diff --git a/src/sagemaker/jumpstart/artifacts/image_uris.py b/src/sagemaker/jumpstart/artifacts/image_uris.py
index 6ea1ca84a1..9d19d5e069 100644
--- a/src/sagemaker/jumpstart/artifacts/image_uris.py
+++ b/src/sagemaker/jumpstart/artifacts/image_uris.py
@@ -17,13 +17,13 @@
 from sagemaker import image_uris
 from sagemaker.jumpstart.constants import (
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
-    JUMPSTART_DEFAULT_REGION_NAME,
 )
 from sagemaker.jumpstart.enums import (
     JumpStartScriptScope,
     ModelFramework,
 )
 from sagemaker.jumpstart.utils import (
+    get_region_fallback,
     verify_model_region_and_return_specs,
 )
 from sagemaker.session import Session
@@ -104,8 +104,9 @@ def _retrieve_image_uri(
             known security vulnerabilities.
         DeprecatedJumpStartModelError: If the version of the model is deprecated.
     """
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
diff --git a/src/sagemaker/jumpstart/artifacts/incremental_training.py b/src/sagemaker/jumpstart/artifacts/incremental_training.py
index 753a911422..1b3c6f4b29 100644
--- a/src/sagemaker/jumpstart/artifacts/incremental_training.py
+++ b/src/sagemaker/jumpstart/artifacts/incremental_training.py
@@ -15,12 +15,12 @@
 from typing import Optional
 from sagemaker.jumpstart.constants import (
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
-    JUMPSTART_DEFAULT_REGION_NAME,
 )
 from sagemaker.jumpstart.enums import (
     JumpStartScriptScope,
 )
 from sagemaker.jumpstart.utils import (
+    get_region_fallback,
     verify_model_region_and_return_specs,
 )
 from sagemaker.session import Session
@@ -58,8 +58,9 @@ def _model_supports_incremental_training(
         bool: the support status for incremental training.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
diff --git a/src/sagemaker/jumpstart/artifacts/instance_types.py b/src/sagemaker/jumpstart/artifacts/instance_types.py
index 608303c5e6..e7c9c5911d 100644
--- a/src/sagemaker/jumpstart/artifacts/instance_types.py
+++ b/src/sagemaker/jumpstart/artifacts/instance_types.py
@@ -18,13 +18,13 @@
 from sagemaker.jumpstart.exceptions import NO_AVAILABLE_INSTANCES_ERROR_MSG
 from sagemaker.jumpstart.constants import (
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
-    JUMPSTART_DEFAULT_REGION_NAME,
 )
 from sagemaker.jumpstart.enums import (
     JumpStartScriptScope,
     JumpStartModelType,
 )
 from sagemaker.jumpstart.utils import (
+    get_region_fallback,
     verify_model_region_and_return_specs,
 )
 from sagemaker.session import Session
@@ -76,8 +76,9 @@ def _retrieve_default_instance_type(
             specified region due to lack of supported computing instances.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
@@ -163,8 +164,9 @@ def _retrieve_instance_types(
             specified region due to lack of supported computing instances.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
diff --git a/src/sagemaker/jumpstart/artifacts/kwargs.py b/src/sagemaker/jumpstart/artifacts/kwargs.py
index c15f686805..9cd152b0bb 100644
--- a/src/sagemaker/jumpstart/artifacts/kwargs.py
+++ b/src/sagemaker/jumpstart/artifacts/kwargs.py
@@ -18,13 +18,13 @@
 from sagemaker.utils import volume_size_supported
 from sagemaker.jumpstart.constants import (
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
-    JUMPSTART_DEFAULT_REGION_NAME,
 )
 from sagemaker.jumpstart.enums import (
     JumpStartScriptScope,
     JumpStartModelType,
 )
 from sagemaker.jumpstart.utils import (
+    get_region_fallback,
     verify_model_region_and_return_specs,
 )
 
@@ -62,8 +62,9 @@ def _retrieve_model_init_kwargs(
         dict: the kwargs to use for the use case.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
@@ -121,8 +122,9 @@ def _retrieve_model_deploy_kwargs(
         dict: the kwargs to use for the use case.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
@@ -176,8 +178,9 @@ def _retrieve_estimator_init_kwargs(
         dict: the kwargs to use for the use case.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
@@ -233,8 +236,9 @@ def _retrieve_estimator_fit_kwargs(
         dict: the kwargs to use for the use case.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
diff --git a/src/sagemaker/jumpstart/artifacts/metric_definitions.py b/src/sagemaker/jumpstart/artifacts/metric_definitions.py
index b6f6019641..57f66155c7 100644
--- a/src/sagemaker/jumpstart/artifacts/metric_definitions.py
+++ b/src/sagemaker/jumpstart/artifacts/metric_definitions.py
@@ -16,12 +16,12 @@
 from typing import Dict, List, Optional
 from sagemaker.jumpstart.constants import (
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
-    JUMPSTART_DEFAULT_REGION_NAME,
 )
 from sagemaker.jumpstart.enums import (
     JumpStartScriptScope,
 )
 from sagemaker.jumpstart.utils import (
+    get_region_fallback,
     verify_model_region_and_return_specs,
 )
 from sagemaker.session import Session
@@ -62,8 +62,9 @@ def _retrieve_default_training_metric_definitions(
         list: the default training metric definitions to use for the model or None.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
diff --git a/src/sagemaker/jumpstart/artifacts/model_packages.py b/src/sagemaker/jumpstart/artifacts/model_packages.py
index 5c8a2488c6..aa22351771 100644
--- a/src/sagemaker/jumpstart/artifacts/model_packages.py
+++ b/src/sagemaker/jumpstart/artifacts/model_packages.py
@@ -15,9 +15,9 @@
 from typing import Optional
 from sagemaker.jumpstart.constants import (
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
-    JUMPSTART_DEFAULT_REGION_NAME,
 )
 from sagemaker.jumpstart.utils import (
+    get_region_fallback,
     verify_model_region_and_return_specs,
 )
 from sagemaker.jumpstart.enums import (
@@ -65,8 +65,9 @@ def _retrieve_model_package_arn(
         str: the model package arn to use for the model or None.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
@@ -149,8 +150,9 @@ def _retrieve_model_package_model_artifact_s3_uri(
 
     if scope == JumpStartScriptScope.TRAINING:
 
-        if region is None:
-            region = JUMPSTART_DEFAULT_REGION_NAME
+        region = region or get_region_fallback(
+            sagemaker_session=sagemaker_session,
+        )
 
         model_specs = verify_model_region_and_return_specs(
             model_id=model_id,
diff --git a/src/sagemaker/jumpstart/artifacts/model_uris.py b/src/sagemaker/jumpstart/artifacts/model_uris.py
index c41f0a75b7..6bb2e576fc 100644
--- a/src/sagemaker/jumpstart/artifacts/model_uris.py
+++ b/src/sagemaker/jumpstart/artifacts/model_uris.py
@@ -18,7 +18,6 @@
 from sagemaker.jumpstart.constants import (
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
     ENV_VARIABLE_JUMPSTART_MODEL_ARTIFACT_BUCKET_OVERRIDE,
-    JUMPSTART_DEFAULT_REGION_NAME,
 )
 from sagemaker.jumpstart.enums import (
     JumpStartScriptScope,
@@ -26,6 +25,7 @@
 from sagemaker.jumpstart.utils import (
     get_jumpstart_content_bucket,
     get_jumpstart_gated_content_bucket,
+    get_region_fallback,
     verify_model_region_and_return_specs,
 )
 from sagemaker.session import Session
@@ -129,8 +129,9 @@ def _retrieve_model_uri(
             known security vulnerabilities.
         DeprecatedJumpStartModelError: If the version of the model is deprecated.
     """
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
@@ -206,8 +207,9 @@ def _model_supports_training_model_uri(
         bool: the support status for model uri with training.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
diff --git a/src/sagemaker/jumpstart/artifacts/payloads.py b/src/sagemaker/jumpstart/artifacts/payloads.py
index 0424145119..3359e32732 100644
--- a/src/sagemaker/jumpstart/artifacts/payloads.py
+++ b/src/sagemaker/jumpstart/artifacts/payloads.py
@@ -16,7 +16,6 @@
 from typing import Dict, Optional
 from sagemaker.jumpstart.constants import (
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
-    JUMPSTART_DEFAULT_REGION_NAME,
 )
 from sagemaker.jumpstart.enums import (
     JumpStartScriptScope,
@@ -24,6 +23,7 @@
 )
 from sagemaker.jumpstart.types import JumpStartSerializablePayload
 from sagemaker.jumpstart.utils import (
+    get_region_fallback,
     verify_model_region_and_return_specs,
 )
 from sagemaker.session import Session
@@ -63,8 +63,9 @@ def _retrieve_example_payloads(
             to the serializable payload object.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
diff --git a/src/sagemaker/jumpstart/artifacts/predictors.py b/src/sagemaker/jumpstart/artifacts/predictors.py
index e9e0e8dfde..4f6dfe1fe3 100644
--- a/src/sagemaker/jumpstart/artifacts/predictors.py
+++ b/src/sagemaker/jumpstart/artifacts/predictors.py
@@ -20,7 +20,6 @@
     CONTENT_TYPE_TO_SERIALIZER_TYPE_MAP,
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
     DESERIALIZER_TYPE_TO_CLASS_MAP,
-    JUMPSTART_DEFAULT_REGION_NAME,
     SERIALIZER_TYPE_TO_CLASS_MAP,
 )
 from sagemaker.jumpstart.enums import (
@@ -29,6 +28,7 @@
     JumpStartModelType,
 )
 from sagemaker.jumpstart.utils import (
+    get_region_fallback,
     verify_model_region_and_return_specs,
 )
 from sagemaker.session import Session
@@ -309,8 +309,9 @@ def _retrieve_default_content_type(
         str: the default content type to use for the model.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
@@ -359,8 +360,9 @@ def _retrieve_default_accept_type(
         str: the default accept type to use for the model.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
@@ -410,8 +412,9 @@ def _retrieve_supported_accept_types(
         list: the supported accept types to use for the model.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
@@ -461,8 +464,9 @@ def _retrieve_supported_content_types(
         list: the supported content types to use for the model.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
diff --git a/src/sagemaker/jumpstart/artifacts/resource_names.py b/src/sagemaker/jumpstart/artifacts/resource_names.py
index 60af520a6e..cffd46d043 100644
--- a/src/sagemaker/jumpstart/artifacts/resource_names.py
+++ b/src/sagemaker/jumpstart/artifacts/resource_names.py
@@ -15,13 +15,13 @@
 from typing import Optional
 from sagemaker.jumpstart.constants import (
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
-    JUMPSTART_DEFAULT_REGION_NAME,
 )
 from sagemaker.jumpstart.enums import (
     JumpStartScriptScope,
     JumpStartModelType,
 )
 from sagemaker.jumpstart.utils import (
+    get_region_fallback,
     verify_model_region_and_return_specs,
 )
 from sagemaker.session import Session
@@ -60,8 +60,9 @@ def _retrieve_resource_name_base(
         str: the default resource name.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
diff --git a/src/sagemaker/jumpstart/artifacts/resource_requirements.py b/src/sagemaker/jumpstart/artifacts/resource_requirements.py
index 9f01a7af77..369acac85f 100644
--- a/src/sagemaker/jumpstart/artifacts/resource_requirements.py
+++ b/src/sagemaker/jumpstart/artifacts/resource_requirements.py
@@ -17,13 +17,13 @@
 
 from sagemaker.jumpstart.constants import (
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
-    JUMPSTART_DEFAULT_REGION_NAME,
 )
 from sagemaker.jumpstart.enums import (
     JumpStartScriptScope,
     JumpStartModelType,
 )
 from sagemaker.jumpstart.utils import (
+    get_region_fallback,
     verify_model_region_and_return_specs,
 )
 from sagemaker.session import Session
@@ -89,8 +89,9 @@ def _retrieve_default_resources(
             retrieve default resource requirements
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
diff --git a/src/sagemaker/jumpstart/artifacts/script_uris.py b/src/sagemaker/jumpstart/artifacts/script_uris.py
index c1b037ce61..f69732d2e0 100644
--- a/src/sagemaker/jumpstart/artifacts/script_uris.py
+++ b/src/sagemaker/jumpstart/artifacts/script_uris.py
@@ -17,13 +17,13 @@
 from sagemaker.jumpstart.constants import (
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
     ENV_VARIABLE_JUMPSTART_SCRIPT_ARTIFACT_BUCKET_OVERRIDE,
-    JUMPSTART_DEFAULT_REGION_NAME,
 )
 from sagemaker.jumpstart.enums import (
     JumpStartScriptScope,
 )
 from sagemaker.jumpstart.utils import (
     get_jumpstart_content_bucket,
+    get_region_fallback,
     verify_model_region_and_return_specs,
 )
 from sagemaker.session import Session
@@ -71,8 +71,9 @@ def _retrieve_script_uri(
             known security vulnerabilities.
         DeprecatedJumpStartModelError: If the version of the model is deprecated.
     """
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
@@ -132,8 +133,9 @@ def _model_supports_inference_script_uri(
         bool: the support status for script uri with inference.
     """
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
diff --git a/src/sagemaker/jumpstart/cache.py b/src/sagemaker/jumpstart/cache.py
index 7682ab3817..fff421ab32 100644
--- a/src/sagemaker/jumpstart/cache.py
+++ b/src/sagemaker/jumpstart/cache.py
@@ -26,7 +26,6 @@
     ENV_VARIABLE_JUMPSTART_SPECS_LOCAL_ROOT_DIR_OVERRIDE,
     JUMPSTART_DEFAULT_MANIFEST_FILE_S3_KEY,
     JUMPSTART_DEFAULT_PROPRIETARY_MANIFEST_KEY,
-    JUMPSTART_DEFAULT_REGION_NAME,
     JUMPSTART_LOGGER,
     MODEL_ID_LIST_WEB_URL,
     MODEL_TYPE_TO_MANIFEST_MAP,
@@ -62,24 +61,21 @@ class JumpStartModelsCache:
     for launching JumpStart models from the SageMaker SDK.
     """
 
-    # fmt: off
     def __init__(
         self,
-        region: str = JUMPSTART_DEFAULT_REGION_NAME,
+        region: Optional[str] = None,
         max_s3_cache_items: int = JUMPSTART_DEFAULT_MAX_S3_CACHE_ITEMS,
-        s3_cache_expiration_horizon: datetime.timedelta =
-        JUMPSTART_DEFAULT_S3_CACHE_EXPIRATION_HORIZON,
-        max_semantic_version_cache_items: int =
-        JUMPSTART_DEFAULT_MAX_SEMANTIC_VERSION_CACHE_ITEMS,
-        semantic_version_cache_expiration_horizon: datetime.timedelta =
-        JUMPSTART_DEFAULT_SEMANTIC_VERSION_CACHE_EXPIRATION_HORIZON,
-        manifest_file_s3_key: str =
-        JUMPSTART_DEFAULT_MANIFEST_FILE_S3_KEY,
+        s3_cache_expiration_horizon: datetime.timedelta = JUMPSTART_DEFAULT_S3_CACHE_EXPIRATION_HORIZON,
+        max_semantic_version_cache_items: int = JUMPSTART_DEFAULT_MAX_SEMANTIC_VERSION_CACHE_ITEMS,
+        semantic_version_cache_expiration_horizon: datetime.timedelta = (
+            JUMPSTART_DEFAULT_SEMANTIC_VERSION_CACHE_EXPIRATION_HORIZON
+        ),
+        manifest_file_s3_key: str = JUMPSTART_DEFAULT_MANIFEST_FILE_S3_KEY,
         proprietary_manifest_s3_key: str = JUMPSTART_DEFAULT_PROPRIETARY_MANIFEST_KEY,
         s3_bucket_name: Optional[str] = None,
         s3_client_config: Optional[botocore.config.Config] = None,
         s3_client: Optional[boto3.client] = None,
-    ) -> None:  # fmt: on
+    ) -> None:
         """Initialize a ``JumpStartModelsCache`` instance.
 
         Args:
@@ -102,7 +98,10 @@ def __init__(
             s3_client (Optional[boto3.client]): s3 client to use. Default: None.
         """
 
-        self._region = region
+        self._region = region or utils.get_region_fallback(
+            s3_bucket_name=s3_bucket_name, s3_client=s3_client
+        )
+
         self._s3_cache = LRUCache[JumpStartCachedS3ContentKey, JumpStartCachedS3ContentValue](
             max_cache_items=max_s3_cache_items,
             expiration_horizon=s3_cache_expiration_horizon,
@@ -165,9 +164,7 @@ def set_manifest_file_s3_key(
         }
         property_name = file_mapping.get(file_type)
         if not property_name:
-            raise ValueError(
-                self._file_type_error_msg(file_type, manifest_only=True)
-            )
+            raise ValueError(self._file_type_error_msg(file_type, manifest_only=True))
         if key != property_name:
             setattr(self, property_name, key)
             self.clear()
@@ -180,9 +177,7 @@ def get_manifest_file_s3_key(
             return self._manifest_file_s3_key
         if file_type == JumpStartS3FileType.PROPRIETARY_MANIFEST:
             return self._proprietary_manifest_s3_key
-        raise ValueError(
-            self._file_type_error_msg(file_type, manifest_only=True)
-        )
+        raise ValueError(self._file_type_error_msg(file_type, manifest_only=True))
 
     def set_s3_bucket_name(self, s3_bucket_name: str) -> None:
         """Set s3 bucket used for cache."""
@@ -235,7 +230,8 @@ def _model_id_retrieval_function(
         sm_version = utils.get_sagemaker_version()
         manifest = self._s3_cache.get(
             JumpStartCachedS3ContentKey(
-                MODEL_TYPE_TO_MANIFEST_MAP[model_type], self._manifest_file_s3_map[model_type])
+                MODEL_TYPE_TO_MANIFEST_MAP[model_type], self._manifest_file_s3_map[model_type]
+            )
         )[0].formatted_content
 
         versions_compatible_with_sagemaker = [
@@ -252,7 +248,8 @@ def _model_id_retrieval_function(
             return JumpStartVersionedModelId(model_id, sm_compatible_model_version)
 
         versions_incompatible_with_sagemaker = [
-            Version(header.version) for header in manifest.values()  # type: ignore
+            Version(header.version)
+            for header in manifest.values()  # type: ignore
             if header.model_id == model_id
         ]
         sm_incompatible_model_version = self._select_version(
@@ -282,9 +279,7 @@ def _model_id_retrieval_function(
             raise KeyError(error_msg)
 
         error_msg = f"Unable to find model manifest for '{model_id}' with version '{version}'. "
-        error_msg += (
-            f"Visit {MODEL_ID_LIST_WEB_URL} for updated list of models. "
-        )
+        error_msg += f"Visit {MODEL_ID_LIST_WEB_URL} for updated list of models. "
 
         other_model_id_version = None
         if model_type == JumpStartModelType.OPEN_WEIGHTS:
@@ -293,19 +288,17 @@ def _model_id_retrieval_function(
             )  # all versions here are incompatible with sagemaker
         elif model_type == JumpStartModelType.PROPRIETARY:
             all_possible_model_id_version = [
-                header.version for header in manifest.values()  # type: ignore
+                header.version
+                for header in manifest.values()  # type: ignore
                 if header.model_id == model_id
             ]
             other_model_id_version = (
-                None
-                if not all_possible_model_id_version
-                else all_possible_model_id_version[0]
+                None if not all_possible_model_id_version else all_possible_model_id_version[0]
             )
 
         if other_model_id_version is not None:
             error_msg += (
-                f"Consider using model ID '{model_id}' with version "
-                f"'{other_model_id_version}'."
+                f"Consider using model ID '{model_id}' with version " f"'{other_model_id_version}'."
             )
         else:
             possible_model_ids = [header.model_id for header in manifest.values()]  # type: ignore
@@ -347,15 +340,15 @@ def _get_json_file_and_etag_from_s3(self, key: str) -> Tuple[Union[dict, list],
 
     def _is_local_metadata_mode(self) -> bool:
         """Returns True if the cache should use local metadata mode, based off env variables."""
-        return (ENV_VARIABLE_JUMPSTART_MANIFEST_LOCAL_ROOT_DIR_OVERRIDE in os.environ
-                and os.path.isdir(os.environ[ENV_VARIABLE_JUMPSTART_MANIFEST_LOCAL_ROOT_DIR_OVERRIDE])
-                and ENV_VARIABLE_JUMPSTART_SPECS_LOCAL_ROOT_DIR_OVERRIDE in os.environ
-                and os.path.isdir(os.environ[ENV_VARIABLE_JUMPSTART_SPECS_LOCAL_ROOT_DIR_OVERRIDE]))
+        return (
+            ENV_VARIABLE_JUMPSTART_MANIFEST_LOCAL_ROOT_DIR_OVERRIDE in os.environ
+            and os.path.isdir(os.environ[ENV_VARIABLE_JUMPSTART_MANIFEST_LOCAL_ROOT_DIR_OVERRIDE])
+            and ENV_VARIABLE_JUMPSTART_SPECS_LOCAL_ROOT_DIR_OVERRIDE in os.environ
+            and os.path.isdir(os.environ[ENV_VARIABLE_JUMPSTART_SPECS_LOCAL_ROOT_DIR_OVERRIDE])
+        )
 
     def _get_json_file(
-        self,
-        key: str,
-        filetype: JumpStartS3FileType
+        self, key: str, filetype: JumpStartS3FileType
     ) -> Tuple[Union[dict, list], Optional[str]]:
         """Returns json file either from s3 or local file system.
 
@@ -379,21 +372,19 @@ def _get_json_md5_hash(self, key: str):
         return self._s3_client.head_object(Bucket=self.s3_bucket_name, Key=key)["ETag"]
 
     def _get_json_file_from_local_override(
-        self,
-        key: str,
-        filetype: JumpStartS3FileType
+        self, key: str, filetype: JumpStartS3FileType
     ) -> Union[dict, list]:
         """Reads json file from local filesystem and returns data."""
         if filetype == JumpStartS3FileType.OPEN_WEIGHT_MANIFEST:
-            metadata_local_root = (
-                os.environ[ENV_VARIABLE_JUMPSTART_MANIFEST_LOCAL_ROOT_DIR_OVERRIDE]
-            )
+            metadata_local_root = os.environ[
+                ENV_VARIABLE_JUMPSTART_MANIFEST_LOCAL_ROOT_DIR_OVERRIDE
+            ]
         elif filetype == JumpStartS3FileType.OPEN_WEIGHT_SPECS:
             metadata_local_root = os.environ[ENV_VARIABLE_JUMPSTART_SPECS_LOCAL_ROOT_DIR_OVERRIDE]
         else:
             raise ValueError(f"Unsupported file type for local override: {filetype}")
         file_path = os.path.join(metadata_local_root, key)
-        with open(file_path, 'r') as f:
+        with open(file_path, "r") as f:
             data = json.load(f)
         return data
 
@@ -437,9 +428,7 @@ def _retrieval_function(
             model_specs = JumpStartModelSpecs(formatted_body)
             utils.emit_logs_based_on_model_specs(model_specs, self.get_region(), self._s3_client)
             return JumpStartCachedS3ContentValue(formatted_content=model_specs)
-        raise ValueError(
-            self._file_type_error_msg(file_type)
-        )
+        raise ValueError(self._file_type_error_msg(file_type))
 
     def get_manifest(
         self,
@@ -448,7 +437,8 @@ def get_manifest(
         """Return entire JumpStart models manifest."""
         manifest_dict = self._s3_cache.get(
             JumpStartCachedS3ContentKey(
-                MODEL_TYPE_TO_MANIFEST_MAP[model_type], self._manifest_file_s3_map[model_type])
+                MODEL_TYPE_TO_MANIFEST_MAP[model_type], self._manifest_file_s3_map[model_type]
+            )
         )[0].formatted_content
         manifest = list(manifest_dict.values())  # type: ignore
         return manifest
@@ -505,16 +495,14 @@ def _select_version(
         except InvalidSpecifier:
             raise KeyError(f"Bad semantic version: {version_str}")
         available_versions_filtered = list(spec.filter(available_versions))
-        return (
-            str(max(available_versions_filtered)) if available_versions_filtered != [] else None
-        )
+        return str(max(available_versions_filtered)) if available_versions_filtered != [] else None
 
     def _get_header_impl(
         self,
         model_id: str,
         semantic_version_str: str,
         attempt: int = 0,
-        model_type: JumpStartModelType = JumpStartModelType.OPEN_WEIGHTS
+        model_type: JumpStartModelType = JumpStartModelType.OPEN_WEIGHTS,
     ) -> JumpStartModelHeader:
         """Lower-level function to return header.
 
@@ -537,7 +525,8 @@ def _get_header_impl(
 
         manifest = self._s3_cache.get(
             JumpStartCachedS3ContentKey(
-                MODEL_TYPE_TO_MANIFEST_MAP[model_type], self._manifest_file_s3_map[model_type])
+                MODEL_TYPE_TO_MANIFEST_MAP[model_type], self._manifest_file_s3_map[model_type]
+            )
         )[0].formatted_content
 
         try:
@@ -553,7 +542,7 @@ def get_specs(
         self,
         model_id: str,
         version_str: str,
-        model_type: JumpStartModelType = JumpStartModelType.OPEN_WEIGHTS
+        model_type: JumpStartModelType = JumpStartModelType.OPEN_WEIGHTS,
     ) -> JumpStartModelSpecs:
         """Return specs for a given JumpStart model ID and semantic version.
 
@@ -566,16 +555,12 @@ def get_specs(
         header = self.get_header(model_id, version_str, model_type)
         spec_key = header.spec_key
         specs, cache_hit = self._s3_cache.get(
-            JumpStartCachedS3ContentKey(
-                MODEL_TYPE_TO_SPECS_MAP[model_type], spec_key
-            )
+            JumpStartCachedS3ContentKey(MODEL_TYPE_TO_SPECS_MAP[model_type], spec_key)
         )
 
         if not cache_hit and "*" in version_str:
             JUMPSTART_LOGGER.warning(
-                get_wildcard_model_version_msg(
-                    header.model_id, version_str, header.version
-                )
+                get_wildcard_model_version_msg(header.model_id, version_str, header.version)
             )
         return specs.formatted_content
 
diff --git a/src/sagemaker/jumpstart/estimator.py b/src/sagemaker/jumpstart/estimator.py
index 4dada409f5..bac076ea4a 100644
--- a/src/sagemaker/jumpstart/estimator.py
+++ b/src/sagemaker/jumpstart/estimator.py
@@ -508,7 +508,7 @@ def _validate_model_id_and_get_type_hook():
             return validate_model_id_and_get_type(
                 model_id=model_id,
                 model_version=model_version,
-                region=region,
+                region=region or getattr(sagemaker_session, "boto_region_name", None),
                 script=JumpStartScriptScope.TRAINING,
                 sagemaker_session=sagemaker_session,
             )
diff --git a/src/sagemaker/jumpstart/factory/estimator.py b/src/sagemaker/jumpstart/factory/estimator.py
index 86630fcfb8..875ec9d003 100644
--- a/src/sagemaker/jumpstart/factory/estimator.py
+++ b/src/sagemaker/jumpstart/factory/estimator.py
@@ -192,8 +192,8 @@ def get_init_kwargs(
 
     estimator_init_kwargs = _add_model_version_to_kwargs(estimator_init_kwargs)
     estimator_init_kwargs = _add_vulnerable_and_deprecated_status_to_kwargs(estimator_init_kwargs)
-    estimator_init_kwargs = _add_region_to_kwargs(estimator_init_kwargs)
     estimator_init_kwargs = _add_sagemaker_session_to_kwargs(estimator_init_kwargs)
+    estimator_init_kwargs = _add_region_to_kwargs(estimator_init_kwargs)
     estimator_init_kwargs = _add_instance_type_and_count_to_kwargs(estimator_init_kwargs)
     estimator_init_kwargs = _add_image_uri_to_kwargs(estimator_init_kwargs)
     estimator_init_kwargs = _add_model_uri_to_kwargs(estimator_init_kwargs)
@@ -393,7 +393,9 @@ def get_deploy_kwargs(
 
 def _add_region_to_kwargs(kwargs: JumpStartKwargs) -> JumpStartKwargs:
     """Sets region in kwargs based on default or override, returns full kwargs."""
-    kwargs.region = kwargs.region or JUMPSTART_DEFAULT_REGION_NAME
+    kwargs.region = (
+        kwargs.region or kwargs.sagemaker_session.boto_region_name or JUMPSTART_DEFAULT_REGION_NAME
+    )
     return kwargs
 
 
@@ -507,6 +509,7 @@ def _add_model_uri_to_kwargs(kwargs: JumpStartEstimatorInitKwargs) -> JumpStartE
             tolerate_deprecated_model=kwargs.tolerate_deprecated_model,
             tolerate_vulnerable_model=kwargs.tolerate_vulnerable_model,
             sagemaker_session=kwargs.sagemaker_session,
+            region=kwargs.region,
             instance_type=kwargs.instance_type,
         )
 
@@ -553,6 +556,7 @@ def _add_source_dir_to_kwargs(kwargs: JumpStartEstimatorInitKwargs) -> JumpStart
         model_version=kwargs.model_version,
         tolerate_deprecated_model=kwargs.tolerate_deprecated_model,
         tolerate_vulnerable_model=kwargs.tolerate_vulnerable_model,
+        region=kwargs.region,
         sagemaker_session=kwargs.sagemaker_session,
     )
 
diff --git a/src/sagemaker/jumpstart/factory/model.py b/src/sagemaker/jumpstart/factory/model.py
index 63b4898877..28746990e3 100644
--- a/src/sagemaker/jumpstart/factory/model.py
+++ b/src/sagemaker/jumpstart/factory/model.py
@@ -129,7 +129,9 @@ def get_default_predictor(
 def _add_region_to_kwargs(kwargs: JumpStartModelInitKwargs) -> JumpStartModelInitKwargs:
     """Sets region kwargs based on default or override, returns full kwargs."""
 
-    kwargs.region = kwargs.region or JUMPSTART_DEFAULT_REGION_NAME
+    kwargs.region = (
+        kwargs.region or kwargs.sagemaker_session.boto_region_name or JUMPSTART_DEFAULT_REGION_NAME
+    )
 
     return kwargs
 
@@ -758,8 +760,8 @@ def get_init_kwargs(
 
     model_init_kwargs = _add_vulnerable_and_deprecated_status_to_kwargs(kwargs=model_init_kwargs)
 
-    model_init_kwargs = _add_region_to_kwargs(kwargs=model_init_kwargs)
     model_init_kwargs = _add_sagemaker_session_to_kwargs(kwargs=model_init_kwargs)
+    model_init_kwargs = _add_region_to_kwargs(kwargs=model_init_kwargs)
 
     model_init_kwargs = _add_model_name_to_kwargs(kwargs=model_init_kwargs)
 
diff --git a/src/sagemaker/jumpstart/model.py b/src/sagemaker/jumpstart/model.py
index a8f4c0e9fc..4529bc11b9 100644
--- a/src/sagemaker/jumpstart/model.py
+++ b/src/sagemaker/jumpstart/model.py
@@ -285,7 +285,7 @@ def _validate_model_id_and_type():
             return validate_model_id_and_get_type(
                 model_id=model_id,
                 model_version=model_version,
-                region=region,
+                region=region or getattr(sagemaker_session, "boto_region_name", None),
                 script=JumpStartScriptScope.INFERENCE,
                 sagemaker_session=sagemaker_session,
             )
diff --git a/src/sagemaker/jumpstart/notebook_utils.py b/src/sagemaker/jumpstart/notebook_utils.py
index 485354e802..85a041379a 100644
--- a/src/sagemaker/jumpstart/notebook_utils.py
+++ b/src/sagemaker/jumpstart/notebook_utils.py
@@ -23,7 +23,6 @@
 from sagemaker.jumpstart import accessors
 from sagemaker.jumpstart.constants import (
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
-    JUMPSTART_DEFAULT_REGION_NAME,
     PROPRIETARY_MODEL_SPEC_PREFIX,
 )
 from sagemaker.jumpstart.enums import JumpStartScriptScope, JumpStartModelType
@@ -38,6 +37,7 @@
 from sagemaker.jumpstart.types import JumpStartModelHeader, JumpStartModelSpecs
 from sagemaker.jumpstart.utils import (
     get_jumpstart_content_bucket,
+    get_region_fallback,
     get_sagemaker_version,
     verify_model_region_and_return_specs,
     validate_model_id_and_get_type,
@@ -156,7 +156,7 @@ def extract_model_type_filter_representation(spec_key: str) -> str:
 
 def list_jumpstart_tasks(  # pylint: disable=redefined-builtin
     filter: Union[Operator, str] = Constant(BooleanValues.TRUE),
-    region: str = JUMPSTART_DEFAULT_REGION_NAME,
+    region: Optional[str] = None,
     sagemaker_session: Session = DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
 ) -> List[str]:
     """List tasks for JumpStart, and optionally apply filters to result.
@@ -168,11 +168,14 @@ def list_jumpstart_tasks(  # pylint: disable=redefined-builtin
             (e.g. ``"task == ic"``). If this argument is not supplied, all tasks will be listed.
             (Default: Constant(BooleanValues.TRUE)).
         region (str): Optional. The AWS region from which to retrieve JumpStart metadata regarding
-            models. (Default: JUMPSTART_DEFAULT_REGION_NAME).
+            models. (Default: None).
         sagemaker_session (sagemaker.session.Session): Optional. The SageMaker Session to
             use to perform the model search. (Default: DEFAULT_JUMPSTART_SAGEMAKER_SESSION).
     """
 
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
     tasks: Set[str] = set()
     for model_id, _ in _generate_jumpstart_model_versions(
         filter=filter, region=region, sagemaker_session=sagemaker_session
@@ -184,7 +187,7 @@ def list_jumpstart_tasks(  # pylint: disable=redefined-builtin
 
 def list_jumpstart_frameworks(  # pylint: disable=redefined-builtin
     filter: Union[Operator, str] = Constant(BooleanValues.TRUE),
-    region: str = JUMPSTART_DEFAULT_REGION_NAME,
+    region: Optional[str] = None,
     sagemaker_session: Session = DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
 ) -> List[str]:
     """List frameworks for JumpStart, and optionally apply filters to result.
@@ -196,11 +199,14 @@ def list_jumpstart_frameworks(  # pylint: disable=redefined-builtin
             (eg. ``"task == ic"``). If this argument is not supplied, all frameworks will be listed.
             (Default: Constant(BooleanValues.TRUE)).
         region (str): Optional. The AWS region from which to retrieve JumpStart metadata regarding
-            models. (Default: JUMPSTART_DEFAULT_REGION_NAME).
+            models. (Default: None).
         sagemaker_session (sagemaker.session.Session): Optional. The SageMaker Session
             to use to perform the model search. (Default: DEFAULT_JUMPSTART_SAGEMAKER_SESSION).
     """
 
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
     frameworks: Set[str] = set()
     for model_id, _ in _generate_jumpstart_model_versions(
         filter=filter, region=region, sagemaker_session=sagemaker_session
@@ -212,7 +218,7 @@ def list_jumpstart_frameworks(  # pylint: disable=redefined-builtin
 
 def list_jumpstart_scripts(  # pylint: disable=redefined-builtin
     filter: Union[Operator, str] = Constant(BooleanValues.TRUE),
-    region: str = JUMPSTART_DEFAULT_REGION_NAME,
+    region: Optional[str] = None,
     sagemaker_session: Session = DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
 ) -> List[str]:
     """List scripts for JumpStart, and optionally apply filters to result.
@@ -224,10 +230,13 @@ def list_jumpstart_scripts(  # pylint: disable=redefined-builtin
             (e.g. ``"task == ic"``). If this argument is not supplied, all scripts will be listed.
             (Default: Constant(BooleanValues.TRUE)).
         region (str): Optional. The AWS region from which to retrieve JumpStart metadata regarding
-            models. (Default: JUMPSTART_DEFAULT_REGION_NAME).
+            models. (Default: None).
         sagemaker_session (sagemaker.session.Session): Optional. The SageMaker Session to
             use to perform the model search. (Default: DEFAULT_JUMPSTART_SAGEMAKER_SESSION).
     """
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
     if (isinstance(filter, Constant) and filter.resolved_value == BooleanValues.TRUE) or (
         isinstance(filter, str) and filter.lower() == BooleanValues.TRUE.lower()
     ):
@@ -255,7 +264,7 @@ def list_jumpstart_scripts(  # pylint: disable=redefined-builtin
 
 def list_jumpstart_models(  # pylint: disable=redefined-builtin
     filter: Union[Operator, str] = Constant(BooleanValues.TRUE),
-    region: str = JUMPSTART_DEFAULT_REGION_NAME,
+    region: Optional[str] = None,
     list_incomplete_models: bool = False,
     list_old_models: bool = False,
     list_versions: bool = False,
@@ -270,7 +279,7 @@ def list_jumpstart_models(  # pylint: disable=redefined-builtin
             (e.g. ``"task == ic"``). If this argument is not supplied, all models will be listed.
             (Default: Constant(BooleanValues.TRUE)).
         region (str): Optional. The AWS region from which to retrieve JumpStart metadata regarding
-            models. (Default: JUMPSTART_DEFAULT_REGION_NAME).
+            models. (Default: None).
         list_incomplete_models (bool): Optional. If a model does not contain metadata fields
             requested by the filter, and the filter cannot be resolved to a include/not include,
             whether the model should be included. By default, these models are omitted from results.
@@ -283,6 +292,9 @@ def list_jumpstart_models(  # pylint: disable=redefined-builtin
             to perform the model search. (Default: DEFAULT_JUMPSTART_SAGEMAKER_SESSION).
     """
 
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
     model_id_version_dict: Dict[str, List[str]] = dict()
     for model_id, version in _generate_jumpstart_model_versions(
         filter=filter,
@@ -312,7 +324,7 @@ def list_jumpstart_models(  # pylint: disable=redefined-builtin
 
 def _generate_jumpstart_model_versions(  # pylint: disable=redefined-builtin
     filter: Union[Operator, str] = Constant(BooleanValues.TRUE),
-    region: str = JUMPSTART_DEFAULT_REGION_NAME,
+    region: Optional[str] = None,
     list_incomplete_models: bool = False,
     sagemaker_session: Session = DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
 ) -> Generator:
@@ -325,7 +337,7 @@ def _generate_jumpstart_model_versions(  # pylint: disable=redefined-builtin
             (e.g. ``"task == ic"``). If this argument is not supplied, all models will be generated.
             (Default: Constant(BooleanValues.TRUE)).
         region (str): Optional. The AWS region from which to retrieve JumpStart metadata regarding
-            models. (Default: JUMPSTART_DEFAULT_REGION_NAME).
+            models. (Default: None).
         list_incomplete_models (bool): Optional. If a model does not contain metadata fields
             requested by the filter, and the filter cannot be resolved to a include/not include,
             whether the model should be included. By default, these models are omitted from
@@ -334,6 +346,10 @@ def _generate_jumpstart_model_versions(  # pylint: disable=redefined-builtin
             to use to perform the model search. (Default: DEFAULT_JUMPSTART_SAGEMAKER_SESSION).
     """
 
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
+
     prop_models_manifest_list = accessors.JumpStartModelsAccessor._get_manifest(
         region=region,
         s3_client=sagemaker_session.s3_client,
@@ -484,7 +500,7 @@ def evaluate_model(model_manifest: JumpStartModelHeader) -> Optional[Tuple[str,
 def get_model_url(
     model_id: str,
     model_version: str,
-    region: str = JUMPSTART_DEFAULT_REGION_NAME,
+    region: Optional[str] = None,
     sagemaker_session: Session = DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
 ) -> str:
     """Retrieve web url describing pretrained model.
@@ -493,7 +509,7 @@ def get_model_url(
         model_id (str): The model ID for which to retrieve the url.
         model_version (str): The model version for which to retrieve the url.
         region (str): Optional. The region from which to retrieve metadata.
-            (Default: JUMPSTART_DEFAULT_REGION_NAME)
+            (Default: None)
         sagemaker_session (sagemaker.session.Session): Optional. The SageMaker Session to use
             to retrieve the model url.
     """
@@ -504,6 +520,9 @@ def get_model_url(
         sagemaker_session=sagemaker_session,
     )
 
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
     model_specs = verify_model_region_and_return_specs(
         region=region,
         model_id=model_id,
diff --git a/src/sagemaker/jumpstart/payload_utils.py b/src/sagemaker/jumpstart/payload_utils.py
index 242118c56e..595f801598 100644
--- a/src/sagemaker/jumpstart/payload_utils.py
+++ b/src/sagemaker/jumpstart/payload_utils.py
@@ -22,12 +22,12 @@
 from sagemaker.jumpstart.artifacts.payloads import _retrieve_example_payloads
 from sagemaker.jumpstart.constants import (
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
-    JUMPSTART_DEFAULT_REGION_NAME,
 )
 from sagemaker.jumpstart.enums import MIMEType
 from sagemaker.jumpstart.types import JumpStartSerializablePayload
 from sagemaker.jumpstart.utils import (
     get_jumpstart_content_bucket,
+    get_region_fallback,
 )
 from sagemaker.session import Session
 
@@ -125,12 +125,14 @@ class PayloadSerializer:
     def __init__(
         self,
         bucket: Optional[str] = None,
-        region: str = JUMPSTART_DEFAULT_REGION_NAME,
+        region: Optional[str] = None,
         s3_client: Optional[boto3.client] = None,
     ) -> None:
         """Initializes PayloadSerializer object."""
         self.bucket = bucket or get_jumpstart_content_bucket()
-        self.region = region
+        self.region = region or get_region_fallback(
+            s3_client=s3_client,
+        )
         self.s3_client = s3_client
 
     def get_bytes_payload_with_s3_references(
diff --git a/src/sagemaker/jumpstart/utils.py b/src/sagemaker/jumpstart/utils.py
index 62ccba7900..5f51173b24 100644
--- a/src/sagemaker/jumpstart/utils.py
+++ b/src/sagemaker/jumpstart/utils.py
@@ -540,7 +540,7 @@ def verify_model_region_and_return_specs(
     model_id: Optional[str],
     version: Optional[str],
     scope: Optional[str],
-    region: str,
+    region: Optional[str] = None,
     tolerate_vulnerable_model: bool = False,
     tolerate_deprecated_model: bool = False,
     sagemaker_session: Session = constants.DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
@@ -576,6 +576,10 @@ def verify_model_region_and_return_specs(
         DeprecatedJumpStartModelError: If the version of the model is deprecated.
     """
 
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
+
     if scope is None:
         raise ValueError(
             "Must specify `model_scope` argument to retrieve model "
@@ -842,3 +846,42 @@ def get_jumpstart_model_id_version_from_resource_arn(
             model_version = model_version_from_tag
 
     return model_id, model_version
+
+
+def get_region_fallback(
+    s3_bucket_name: Optional[str] = None,
+    s3_client: Optional[boto3.client] = None,
+    sagemaker_session: Optional[Session] = None,
+) -> str:
+    """Returns region to use for JumpStart functionality implicitly via session objects."""
+    regions_in_s3_bucket_name: Set[str] = {
+        region
+        for region in constants.JUMPSTART_REGION_NAME_SET
+        if s3_bucket_name is not None
+        if region in s3_bucket_name
+    }
+    regions_in_s3_client_endpoint_url: Set[str] = {
+        region
+        for region in constants.JUMPSTART_REGION_NAME_SET
+        if s3_client is not None
+        if region in s3_client._endpoint.host
+    }
+
+    regions_in_sagemaker_session: Set[str] = {
+        region
+        for region in constants.JUMPSTART_REGION_NAME_SET
+        if sagemaker_session
+        if region == sagemaker_session.boto_region_name
+    }
+
+    combined_regions = regions_in_s3_client_endpoint_url.union(
+        regions_in_s3_bucket_name, regions_in_sagemaker_session
+    )
+
+    if len(combined_regions) > 1:
+        raise ValueError("Unable to resolve a region name from the s3 bucket and client provided.")
+
+    if len(combined_regions) == 0:
+        return constants.JUMPSTART_DEFAULT_REGION_NAME
+
+    return list(combined_regions)[0]
diff --git a/src/sagemaker/jumpstart/validators.py b/src/sagemaker/jumpstart/validators.py
index 3199e5fc2e..c7098a1185 100644
--- a/src/sagemaker/jumpstart/validators.py
+++ b/src/sagemaker/jumpstart/validators.py
@@ -14,7 +14,6 @@
 from __future__ import absolute_import
 from typing import Any, Dict, List, Optional
 from sagemaker import session
-from sagemaker.jumpstart.constants import JUMPSTART_DEFAULT_REGION_NAME
 
 from sagemaker.jumpstart.enums import (
     HyperparameterValidationMode,
@@ -24,7 +23,7 @@
 )
 from sagemaker.jumpstart.exceptions import JumpStartHyperparametersError
 from sagemaker.jumpstart.types import JumpStartHyperparameter
-from sagemaker.jumpstart.utils import verify_model_region_and_return_specs
+from sagemaker.jumpstart.utils import get_region_fallback, verify_model_region_and_return_specs
 
 
 def _validate_hyperparameter(
@@ -168,7 +167,7 @@ def validate_hyperparameters(
     model_version: str,
     hyperparameters: Dict[str, Any],
     validation_mode: HyperparameterValidationMode = HyperparameterValidationMode.VALIDATE_PROVIDED,
-    region: Optional[str] = JUMPSTART_DEFAULT_REGION_NAME,
+    region: Optional[str] = None,
     sagemaker_session: Optional[session.Session] = None,
     tolerate_vulnerable_model: bool = False,
     tolerate_deprecated_model: bool = False,
@@ -184,8 +183,7 @@ def validate_hyperparameters(
           to this function will be validated, the missing hyperparameters will be ignored.
           If set to``VALIDATE_ALGORITHM``, all algorithm hyperparameters will be validated.
           If set to ``VALIDATE_ALL``, all hyperparameters for the model will be validated.
-        region (str): Region for which to validate hyperparameters. (Default: JumpStart
-          default region).
+        region (str): Region for which to validate hyperparameters. (Default: None).
         sagemaker_session (Optional[Session]): Custom SageMaker Session to use.
           (Default: sagemaker.jumpstart.constants.DEFAULT_JUMPSTART_SAGEMAKER_SESSION).
         tolerate_vulnerable_model (bool): True if vulnerable versions of model
@@ -202,11 +200,15 @@ def validate_hyperparameters(
 
     """
 
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
     if validation_mode is None:
         validation_mode = HyperparameterValidationMode.VALIDATE_PROVIDED
 
-    if region is None:
-        region = JUMPSTART_DEFAULT_REGION_NAME
+    region = region or get_region_fallback(
+        sagemaker_session=sagemaker_session,
+    )
 
     model_specs = verify_model_region_and_return_specs(
         model_id=model_id,
diff --git a/tests/unit/sagemaker/accept_types/jumpstart/test_accept_types.py b/tests/unit/sagemaker/accept_types/jumpstart/test_accept_types.py
index 49c18beec2..11165a0625 100644
--- a/tests/unit/sagemaker/accept_types/jumpstart/test_accept_types.py
+++ b/tests/unit/sagemaker/accept_types/jumpstart/test_accept_types.py
@@ -23,7 +23,8 @@
 
 
 mock_client = boto3.client("s3")
-mock_session = Mock(s3_client=mock_client)
+region = "us-west-2"
+mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
 
 @patch("sagemaker.jumpstart.utils.validate_model_id_and_get_type")
diff --git a/tests/unit/sagemaker/content_types/jumpstart/test_content_types.py b/tests/unit/sagemaker/content_types/jumpstart/test_content_types.py
index 7765d6eaad..d116c8121b 100644
--- a/tests/unit/sagemaker/content_types/jumpstart/test_content_types.py
+++ b/tests/unit/sagemaker/content_types/jumpstart/test_content_types.py
@@ -22,7 +22,8 @@
 from tests.unit.sagemaker.jumpstart.utils import get_special_model_spec
 
 mock_client = boto3.client("s3")
-mock_session = Mock(s3_client=mock_client)
+region = "us-west-2"
+mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
 
 @patch("sagemaker.jumpstart.utils.validate_model_id_and_get_type")
diff --git a/tests/unit/sagemaker/deserializers/jumpstart/test_deserializers.py b/tests/unit/sagemaker/deserializers/jumpstart/test_deserializers.py
index 5328533da5..f0102068e7 100644
--- a/tests/unit/sagemaker/deserializers/jumpstart/test_deserializers.py
+++ b/tests/unit/sagemaker/deserializers/jumpstart/test_deserializers.py
@@ -22,9 +22,10 @@
 
 from tests.unit.sagemaker.jumpstart.utils import get_special_model_spec
 
+region = "us-west-2"
 
 mock_client = boto3.client("s3")
-mock_session = Mock(s3_client=mock_client)
+mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
 
 @patch("sagemaker.jumpstart.utils.validate_model_id_and_get_type")
diff --git a/tests/unit/sagemaker/environment_variables/jumpstart/test_default.py b/tests/unit/sagemaker/environment_variables/jumpstart/test_default.py
index cc1aad8a44..5f00f93abf 100644
--- a/tests/unit/sagemaker/environment_variables/jumpstart/test_default.py
+++ b/tests/unit/sagemaker/environment_variables/jumpstart/test_default.py
@@ -25,7 +25,8 @@
 
 
 mock_client = boto3.client("s3")
-mock_session = Mock(s3_client=mock_client)
+region = "us-west-2"
+mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
 
 @patch("sagemaker.jumpstart.utils.validate_model_id_and_get_type")
diff --git a/tests/unit/sagemaker/hyperparameters/jumpstart/test_default.py b/tests/unit/sagemaker/hyperparameters/jumpstart/test_default.py
index a13fba87ae..40ee4978cf 100644
--- a/tests/unit/sagemaker/hyperparameters/jumpstart/test_default.py
+++ b/tests/unit/sagemaker/hyperparameters/jumpstart/test_default.py
@@ -24,7 +24,8 @@
 
 
 mock_client = boto3.client("s3")
-mock_session = Mock(s3_client=mock_client)
+region = "us-west-2"
+mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
 
 @patch("sagemaker.jumpstart.utils.validate_model_id_and_get_type")
diff --git a/tests/unit/sagemaker/hyperparameters/jumpstart/test_validate.py b/tests/unit/sagemaker/hyperparameters/jumpstart/test_validate.py
index 7a5df4ac93..07418f8ddb 100644
--- a/tests/unit/sagemaker/hyperparameters/jumpstart/test_validate.py
+++ b/tests/unit/sagemaker/hyperparameters/jumpstart/test_validate.py
@@ -23,8 +23,9 @@
 
 from tests.unit.sagemaker.jumpstart.utils import get_spec_from_base_spec
 
+region = "us-west-2"
 mock_client = boto3.client("s3")
-mock_session = Mock(s3_client=mock_client)
+mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
 
 @patch("sagemaker.jumpstart.utils.validate_model_id_and_get_type")
diff --git a/tests/unit/sagemaker/image_uris/jumpstart/test_common.py b/tests/unit/sagemaker/image_uris/jumpstart/test_common.py
index 6c80c97f33..88b95b9403 100644
--- a/tests/unit/sagemaker/image_uris/jumpstart/test_common.py
+++ b/tests/unit/sagemaker/image_uris/jumpstart/test_common.py
@@ -37,8 +37,9 @@ def test_jumpstart_common_image_uri(
     patched_get_model_specs.side_effect = get_spec_from_base_spec
     patched_validate_model_id_and_get_type.return_value = JumpStartModelType.OPEN_WEIGHTS
 
+    region = "us-west-2"
     mock_client = boto3.client("s3")
-    mock_session = Mock(s3_client=mock_client)
+    mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
     image_uris.retrieve(
         framework=None,
diff --git a/tests/unit/sagemaker/instance_types/jumpstart/test_instance_types.py b/tests/unit/sagemaker/instance_types/jumpstart/test_instance_types.py
index 982c7f1702..2e51afd3f7 100644
--- a/tests/unit/sagemaker/instance_types/jumpstart/test_instance_types.py
+++ b/tests/unit/sagemaker/instance_types/jumpstart/test_instance_types.py
@@ -34,7 +34,7 @@ def test_jumpstart_instance_types(patched_get_model_specs, patched_validate_mode
     region = "us-west-2"
 
     mock_client = boto3.client("s3")
-    mock_session = Mock(s3_client=mock_client)
+    mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
     default_training_instance_types = instance_types.retrieve_default(
         region=region,
@@ -178,7 +178,8 @@ def test_jumpstart_inference_instance_type_variants(patched_get_model_specs):
     patched_get_model_specs.side_effect = get_special_model_spec
 
     mock_client = boto3.client("s3")
-    mock_session = Mock(s3_client=mock_client)
+    region = "us-west-2"
+    mock_session = Mock(s3_client=mock_client, boto_region_name=region)
     model_id, model_version = "inference-instance-types-variant-model", "*"
     region = "us-west-2"
 
diff --git a/tests/unit/sagemaker/jumpstart/estimator/test_estimator.py b/tests/unit/sagemaker/jumpstart/estimator/test_estimator.py
index fe4b122c4a..1e048ef0dd 100644
--- a/tests/unit/sagemaker/jumpstart/estimator/test_estimator.py
+++ b/tests/unit/sagemaker/jumpstart/estimator/test_estimator.py
@@ -16,6 +16,7 @@
 from unittest import mock
 import unittest
 from inspect import signature
+from mock import Mock
 
 import pytest
 from sagemaker.async_inference.async_inference_config import AsyncInferenceConfig
@@ -30,12 +31,16 @@
 from sagemaker.jumpstart.artifacts.metric_definitions import (
     _retrieve_default_training_metric_definitions,
 )
-from sagemaker.jumpstart.constants import DEFAULT_JUMPSTART_SAGEMAKER_SESSION
+from sagemaker.jumpstart.constants import (
+    DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
+    JUMPSTART_DEFAULT_REGION_NAME,
+)
 from sagemaker.jumpstart.enums import JumpStartScriptScope, JumpStartTag, JumpStartModelType
 
 from sagemaker.jumpstart.estimator import JumpStartEstimator
 
 from sagemaker.jumpstart.utils import get_jumpstart_content_bucket
+from sagemaker.session import Session
 from sagemaker.session_settings import SessionSettings
 from tests.integ.sagemaker.jumpstart.utils import get_training_dataset_for_model_and_version
 from sagemaker.model import Model
@@ -44,6 +49,7 @@
     get_special_model_spec,
     overwrite_dictionary,
 )
+import boto3
 
 
 execution_role = "fake role! do not use!"
@@ -1553,7 +1559,8 @@ def test_training_passes_session_to_deploy(
         mock_get_model_specs.side_effect = get_special_model_spec
 
         mock_role = f"dsfsdfsd{time.time()}"
-        mock_sagemaker_session = mock.MagicMock(sagemaker_config={})
+        region = "us-west-2"
+        mock_sagemaker_session = mock.MagicMock(sagemaker_config={}, boto_region_name=region)
         mock_sagemaker_session.get_caller_identity_arn = lambda: mock_role
 
         estimator = JumpStartEstimator(
@@ -1758,6 +1765,56 @@ def test_model_artifact_variant_estimator(
             ],
         )
 
+    @mock.patch("sagemaker.jumpstart.estimator.get_default_predictor")
+    @mock.patch("sagemaker.jumpstart.estimator.Estimator.__init__")
+    @mock.patch("sagemaker.jumpstart.estimator.Estimator.fit")
+    @mock.patch("sagemaker.jumpstart.estimator.Estimator.deploy")
+    @mock.patch("sagemaker.jumpstart.estimator.validate_model_id_and_get_type")
+    @mock.patch("sagemaker.jumpstart.accessors.JumpStartModelsAccessor.get_model_specs")
+    @mock.patch("sagemaker.jumpstart.factory.model.JUMPSTART_DEFAULT_REGION_NAME", region)
+    def test_jumpstart_estimator_session(
+        self,
+        mock_get_model_specs: mock.Mock,
+        mock_validate_model_id_and_get_type: mock.Mock,
+        mock_deploy,
+        mock_fit,
+        mock_init,
+        get_default_predictor,
+    ):
+
+        mock_validate_model_id_and_get_type.return_value = True
+
+        model_id, _ = "js-trainable-model", "*"
+
+        mock_get_model_specs.side_effect = get_special_model_spec
+
+        region = "eu-west-1"  # some non-default region
+
+        if region == JUMPSTART_DEFAULT_REGION_NAME:
+            region = "us-west-2"
+
+        session = Session(boto_session=boto3.session.Session(region_name=region))
+
+        assert session.boto_region_name != JUMPSTART_DEFAULT_REGION_NAME
+
+        session.get_caller_identity_arn = Mock(return_value="blah")
+
+        estimator = JumpStartEstimator(model_id=model_id, sagemaker_session=session)
+        estimator.fit()
+
+        estimator.deploy()
+
+        assert len(mock_get_model_specs.call_args_list) > 1
+
+        regions = {call[1]["region"] for call in mock_get_model_specs.call_args_list}
+
+        assert len(regions) == 1
+        assert list(regions)[0] == region
+
+        s3_clients = {call[1]["s3_client"] for call in mock_get_model_specs.call_args_list}
+        assert len(s3_clients) == 1
+        assert list(s3_clients)[0] == session.s3_client
+
 
 def test_jumpstart_estimator_requires_model_id():
     with pytest.raises(ValueError):
diff --git a/tests/unit/sagemaker/jumpstart/model/test_model.py b/tests/unit/sagemaker/jumpstart/model/test_model.py
index ba4ba0bb13..c4a96d4120 100644
--- a/tests/unit/sagemaker/jumpstart/model/test_model.py
+++ b/tests/unit/sagemaker/jumpstart/model/test_model.py
@@ -15,18 +15,22 @@
 from typing import Optional, Set
 from unittest import mock
 import unittest
-from mock import MagicMock
+from mock import MagicMock, Mock
 import pytest
 from sagemaker.async_inference.async_inference_config import AsyncInferenceConfig
 from sagemaker.jumpstart.artifacts.environment_variables import (
     _retrieve_default_environment_variables,
 )
-from sagemaker.jumpstart.constants import DEFAULT_JUMPSTART_SAGEMAKER_SESSION
+from sagemaker.jumpstart.constants import (
+    DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
+    JUMPSTART_DEFAULT_REGION_NAME,
+)
 from sagemaker.jumpstart.enums import JumpStartScriptScope, JumpStartTag, JumpStartModelType
 
 from sagemaker.jumpstart.model import JumpStartModel
 from sagemaker.model import Model
 from sagemaker.predictor import Predictor
+from sagemaker.session import Session
 from sagemaker.session_settings import SessionSettings
 from sagemaker.enums import EndpointType
 from sagemaker.compute_resource_requirements.resource_requirements import ResourceRequirements
@@ -38,6 +42,7 @@
     get_special_model_spec_for_inference_component_based_endpoint,
     get_prototype_manifest,
 )
+import boto3
 
 execution_role = "fake role! do not use!"
 region = "us-west-2"
@@ -950,7 +955,7 @@ def test_jumpstart_model_tags(
 
         mock_get_model_specs.side_effect = get_special_model_spec
 
-        mock_session = MagicMock(sagemaker_config={})
+        mock_session = MagicMock(sagemaker_config={}, boto_region_name="us-west-2")
 
         model = JumpStartModel(model_id=model_id, sagemaker_session=mock_session)
 
@@ -987,7 +992,9 @@ def test_jumpstart_model_tags_disabled(
         mock_get_model_specs.side_effect = get_special_model_spec
 
         settings = SessionSettings(include_jumpstart_tags=False)
-        mock_session = MagicMock(sagemaker_config={}, settings=settings)
+        mock_session = MagicMock(
+            sagemaker_config={}, settings=settings, boto_region_name="us-west-2"
+        )
 
         model = JumpStartModel(model_id=model_id, sagemaker_session=mock_session)
 
@@ -1018,7 +1025,7 @@ def test_jumpstart_model_package_arn(
 
         mock_get_model_specs.side_effect = get_special_model_spec
 
-        mock_session = MagicMock(sagemaker_config={})
+        mock_session = MagicMock(sagemaker_config={}, boto_region_name="us-west-2")
 
         model = JumpStartModel(model_id=model_id, sagemaker_session=mock_session)
 
@@ -1053,7 +1060,7 @@ def test_jumpstart_model_package_arn_override(
 
         mock_get_model_specs.side_effect = get_special_model_spec
 
-        mock_session = MagicMock(sagemaker_config={})
+        mock_session = MagicMock(sagemaker_config={}, boto_region_name="us-west-2")
 
         model_package_arn = (
             "arn:aws:sagemaker:us-west-2:867530986753:model-package/"
@@ -1312,6 +1319,52 @@ def test_model_registry_accept_and_response_types(
             response_types=["application/json;verbose", "application/json"],
         )
 
+    @mock.patch("sagemaker.jumpstart.model.get_default_predictor")
+    @mock.patch("sagemaker.jumpstart.model.Model.__init__")
+    @mock.patch("sagemaker.jumpstart.model.Model.deploy")
+    @mock.patch("sagemaker.jumpstart.model.validate_model_id_and_get_type")
+    @mock.patch("sagemaker.jumpstart.accessors.JumpStartModelsAccessor.get_model_specs")
+    @mock.patch("sagemaker.jumpstart.factory.model.JUMPSTART_DEFAULT_REGION_NAME", region)
+    def test_jumpstart_model_session(
+        self,
+        mock_get_model_specs: mock.Mock,
+        mock_validate_model_id_and_get_type: mock.Mock,
+        mock_deploy,
+        mock_init,
+        get_default_predictor,
+    ):
+
+        mock_validate_model_id_and_get_type.return_value = True
+
+        model_id, _ = "model_data_s3_prefix_model", "*"
+
+        mock_get_model_specs.side_effect = get_special_model_spec
+
+        region = "eu-west-1"  # some non-default region
+
+        if region == JUMPSTART_DEFAULT_REGION_NAME:
+            region = "us-west-2"
+
+        session = Session(boto_session=boto3.session.Session(region_name=region))
+
+        assert session.boto_region_name != JUMPSTART_DEFAULT_REGION_NAME
+
+        session.get_caller_identity_arn = Mock(return_value="blah")
+
+        model = JumpStartModel(model_id=model_id, sagemaker_session=session)
+        model.deploy()
+
+        assert len(mock_get_model_specs.call_args_list) > 1
+
+        regions = {call[1]["region"] for call in mock_get_model_specs.call_args_list}
+
+        assert len(regions) == 1
+        assert list(regions)[0] == region
+
+        s3_clients = {call[1]["s3_client"] for call in mock_get_model_specs.call_args_list}
+        assert len(s3_clients) == 1
+        assert list(s3_clients)[0] == session.s3_client
+
 
 def test_jumpstart_model_requires_model_id():
     with pytest.raises(ValueError):
diff --git a/tests/unit/sagemaker/jumpstart/test_artifacts.py b/tests/unit/sagemaker/jumpstart/test_artifacts.py
index 21112926a5..3d9b5cef6a 100644
--- a/tests/unit/sagemaker/jumpstart/test_artifacts.py
+++ b/tests/unit/sagemaker/jumpstart/test_artifacts.py
@@ -329,7 +329,8 @@ def test_estimator_fit_kwargs(self, patched_get_model_specs):
 
 class RetrieveModelPackageArnTest(unittest.TestCase):
 
-    mock_session = Mock(s3_client=mock_client)
+    region = "us-west-2"
+    mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
     @patch("sagemaker.jumpstart.utils.validate_model_id_and_get_type")
     @patch("sagemaker.jumpstart.accessors.JumpStartModelsAccessor.get_model_specs")
@@ -439,7 +440,8 @@ def test_retrieve_model_package_arn(
 
 class PrivateJumpStartBucketTest(unittest.TestCase):
 
-    mock_session = Mock(s3_client=mock_client)
+    region = "us-west-2"
+    mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
     @patch("sagemaker.jumpstart.utils.validate_model_id_and_get_type")
     @patch("sagemaker.jumpstart.accessors.JumpStartModelsAccessor.get_model_specs")
diff --git a/tests/unit/sagemaker/jumpstart/test_utils.py b/tests/unit/sagemaker/jumpstart/test_utils.py
index cb54722d48..c81d5639e5 100644
--- a/tests/unit/sagemaker/jumpstart/test_utils.py
+++ b/tests/unit/sagemaker/jumpstart/test_utils.py
@@ -15,7 +15,9 @@
 from unittest import TestCase
 from mock.mock import Mock, patch
 import pytest
+import boto3
 import random
+from sagemaker import session
 from sagemaker.jumpstart import utils
 from sagemaker.jumpstart.constants import (
     DEFAULT_JUMPSTART_SAGEMAKER_SESSION,
@@ -1450,3 +1452,50 @@ def test_logger_disabled(self, mocked_emit: Mock):
         JUMPSTART_LOGGER.warning("Self destruct in 3...2...1...")
 
         mocked_emit.assert_not_called()
+
+
+@pytest.mark.parametrize(
+    "s3_bucket_name, s3_client, sagemaker_session, region",
+    [
+        (
+            "jumpstart-cache-prod",
+            boto3.client("s3", region_name="blah-blah"),
+            session.Session(boto3.Session(region_name="blah-blah")),
+            JUMPSTART_DEFAULT_REGION_NAME,
+        ),
+        (
+            "jumpstart-cache-prod-us-west-2",
+            boto3.client("s3", region_name="us-west-2"),
+            session.Session(boto3.Session(region_name="us-west-2")),
+            "us-west-2",
+        ),
+        ("jumpstart-cache-prod", boto3.client("s3", region_name="us-east-2"), None, "us-east-2"),
+    ],
+)
+def test_get_region_fallback_success(s3_bucket_name, s3_client, sagemaker_session, region):
+    assert region == utils.get_region_fallback(s3_bucket_name, s3_client, sagemaker_session)
+
+
+@pytest.mark.parametrize(
+    "s3_bucket_name, s3_client, sagemaker_session",
+    [
+        (
+            "jumpstart-cache-prod-us-west-2",
+            boto3.client("s3", region_name="us-east-2"),
+            session.Session(boto3.Session(region_name="us-west-2")),
+        ),
+        (
+            "jumpstart-cache-prod-us-west-2",
+            boto3.client("s3", region_name="us-west-2"),
+            session.Session(boto3.Session(region_name="eu-north-1")),
+        ),
+        (
+            "jumpstart-cache-prod-us-west-2-us-east-2",
+            boto3.client("s3", region_name="us-east-2"),
+            None,
+        ),
+    ],
+)
+def test_get_region_fallback_failure(s3_bucket_name, s3_client, sagemaker_session):
+    with pytest.raises(ValueError):
+        utils.get_region_fallback(s3_bucket_name, s3_client, sagemaker_session)
diff --git a/tests/unit/sagemaker/metric_definitions/jumpstart/test_default.py b/tests/unit/sagemaker/metric_definitions/jumpstart/test_default.py
index 608a32a005..835a09a58c 100644
--- a/tests/unit/sagemaker/metric_definitions/jumpstart/test_default.py
+++ b/tests/unit/sagemaker/metric_definitions/jumpstart/test_default.py
@@ -23,7 +23,8 @@
 from tests.unit.sagemaker.jumpstart.utils import get_spec_from_base_spec, get_special_model_spec
 
 mock_client = boto3.client("s3")
-mock_session = Mock(s3_client=mock_client)
+region = "us-west-2"
+mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
 
 @patch("sagemaker.jumpstart.utils.validate_model_id_and_get_type")
@@ -36,7 +37,8 @@ def test_jumpstart_default_metric_definitions(
     patched_validate_model_id_and_get_type.return_value = JumpStartModelType.OPEN_WEIGHTS
 
     mock_client = boto3.client("s3")
-    mock_session = Mock(s3_client=mock_client)
+    region = "us-west-2"
+    mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
     model_id = "pytorch-ic-mobilenet-v2"
     region = "us-west-2"
diff --git a/tests/unit/sagemaker/model_uris/jumpstart/test_common.py b/tests/unit/sagemaker/model_uris/jumpstart/test_common.py
index 8d75731b06..8ec9478d8a 100644
--- a/tests/unit/sagemaker/model_uris/jumpstart/test_common.py
+++ b/tests/unit/sagemaker/model_uris/jumpstart/test_common.py
@@ -39,7 +39,8 @@ def test_jumpstart_common_model_uri(
     patched_validate_model_id_and_get_type.return_value = JumpStartModelType.OPEN_WEIGHTS
 
     mock_client = boto3.client("s3")
-    mock_session = Mock(s3_client=mock_client)
+    region = "us-west-2"
+    mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
     model_uris.retrieve(
         model_scope="training",
diff --git a/tests/unit/sagemaker/resource_requirements/jumpstart/test_resource_requirements.py b/tests/unit/sagemaker/resource_requirements/jumpstart/test_resource_requirements.py
index 7b5e7a598d..1c0cfa35b3 100644
--- a/tests/unit/sagemaker/resource_requirements/jumpstart/test_resource_requirements.py
+++ b/tests/unit/sagemaker/resource_requirements/jumpstart/test_resource_requirements.py
@@ -37,7 +37,7 @@ def test_jumpstart_resource_requirements(
     patched_validate_model_id_and_get_type.return_value = JumpStartModelType.OPEN_WEIGHTS
     region = "us-west-2"
     mock_client = boto3.client("s3")
-    mock_session = Mock(s3_client=mock_client)
+    mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
     model_id, model_version = "huggingface-llm-mistral-7b-instruct", "*"
     default_inference_resource_requirements = resource_requirements.retrieve_default(
@@ -121,7 +121,7 @@ def test_jumpstart_no_supported_resource_requirements(
     model_id, model_version = "no-supported-instance-types-model", "*"
     region = "us-west-2"
     mock_client = boto3.client("s3")
-    mock_session = Mock(s3_client=mock_client)
+    mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
     default_inference_resource_requirements = resource_requirements.retrieve_default(
         region=region,
diff --git a/tests/unit/sagemaker/script_uris/jumpstart/test_common.py b/tests/unit/sagemaker/script_uris/jumpstart/test_common.py
index c797ba3559..16b7256ed2 100644
--- a/tests/unit/sagemaker/script_uris/jumpstart/test_common.py
+++ b/tests/unit/sagemaker/script_uris/jumpstart/test_common.py
@@ -39,7 +39,8 @@ def test_jumpstart_common_script_uri(
     patched_validate_model_id_and_get_type.return_value = JumpStartModelType.OPEN_WEIGHTS
 
     mock_client = boto3.client("s3")
-    mock_session = Mock(s3_client=mock_client)
+    region = "us-west-2"
+    mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
     script_uris.retrieve(
         script_scope="training",
diff --git a/tests/unit/sagemaker/serializers/jumpstart/test_serializers.py b/tests/unit/sagemaker/serializers/jumpstart/test_serializers.py
index c2253726bf..90ec5df6b5 100644
--- a/tests/unit/sagemaker/serializers/jumpstart/test_serializers.py
+++ b/tests/unit/sagemaker/serializers/jumpstart/test_serializers.py
@@ -40,7 +40,7 @@ def test_jumpstart_default_serializers(
     model_id, model_version = "predictor-specs-model", "*"
     region = "us-west-2"
     mock_client = boto3.client("s3")
-    mock_session = Mock(s3_client=mock_client)
+    mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
     default_serializer = serializers.retrieve_default(
         region=region,
@@ -75,7 +75,8 @@ def test_jumpstart_serializer_options(
     patched_validate_model_id_and_get_type.return_value = JumpStartModelType.OPEN_WEIGHTS
 
     mock_client = boto3.client("s3")
-    mock_session = Mock(s3_client=mock_client)
+    region = "us-west-2"
+    mock_session = Mock(s3_client=mock_client, boto_region_name=region)
 
     model_id, model_version = "predictor-specs-model", "*"
     region = "us-west-2"