diff --git a/packages/cli/generators/rest-crud/index.js b/packages/cli/generators/rest-crud/index.js
index 5a9f921e7341..3692ec95c31d 100644
--- a/packages/cli/generators/rest-crud/index.js
+++ b/packages/cli/generators/rest-crud/index.js
@@ -367,7 +367,19 @@ module.exports = class RestCrudGenerator extends ArtifactGenerator {
         debug(`artifactInfo: ${inspect(this.artifactInfo)}`);
         debug(`Copying artifact to: ${dest}`);
       }
-
+      this.artifactInfo.upsert = false;
+      if (this.options.upsert.includes('*')) {
+        this.artifactInfo.upsert = true;
+      } else {
+        this.options.upsert.forEach(modelName => {
+          if (
+            this.artifactInfo.modelName.toLowerCase() ===
+            modelName.toLowerCase()
+          ) {
+            this.artifactInfo.upsert = true;
+          }
+        });
+      }
       this.copyTemplatedFiles(source, dest, this.artifactInfo);
     }
 
diff --git a/packages/cli/generators/rest-crud/templates/src/model-endpoints/model.rest-config-template.ts.ejs b/packages/cli/generators/rest-crud/templates/src/model-endpoints/model.rest-config-template.ts.ejs
index 703a5f1112c8..858f45d6b2d9 100644
--- a/packages/cli/generators/rest-crud/templates/src/model-endpoints/model.rest-config-template.ts.ejs
+++ b/packages/cli/generators/rest-crud/templates/src/model-endpoints/model.rest-config-template.ts.ejs
@@ -7,5 +7,6 @@ const config: ModelCrudRestApiConfig = {
   dataSource: '<%= dataSourceName %>',
   basePath: '<%= basePath %>',
   readonly: <%= readonly %>,
+  upsert: <%= upsert %>,
 };
 module.exports = config;
diff --git a/packages/repository/src/connectors/crud.connector.ts b/packages/repository/src/connectors/crud.connector.ts
index 6ebf61060479..2971cf0f263f 100644
--- a/packages/repository/src/connectors/crud.connector.ts
+++ b/packages/repository/src/connectors/crud.connector.ts
@@ -25,6 +25,19 @@ export interface CrudConnector extends Connector {
     options?: Options,
   ): Promise<EntityData>;
 
+  /**
+   * Update an existing entity or Create if it does not exist
+   * @param modelClass - The model class
+   * @param entity - The entity instance or data
+   * @param options - Options for the operation
+   * @returns A promise of the entity created
+   */
+  upsert(
+    modelClass: Class<Entity>,
+    entity: EntityData,
+    options?: Options,
+  ): Promise<EntityData>;
+
   /**
    * Create multiple entities
    * @param modelClass - The model class
diff --git a/packages/repository/src/repositories/legacy-juggler-bridge.ts b/packages/repository/src/repositories/legacy-juggler-bridge.ts
index 3df52ed95514..6dec226cd2f4 100644
--- a/packages/repository/src/repositories/legacy-juggler-bridge.ts
+++ b/packages/repository/src/repositories/legacy-juggler-bridge.ts
@@ -493,6 +493,12 @@ export class DefaultCrudRepository<
     return this.toEntity(model);
   }
 
+  async upsert(entity: DataObject<T>, options?: Options): Promise<T> {
+    const data = await this.entityToData(entity, options);
+    const model = await ensurePromise(this.modelClass.upsert(data, options));
+    return this.toEntity(model);
+  }
+
   async createAll(entities: DataObject<T>[], options?: Options): Promise<T[]> {
     // perform persist hook
     const data = await Promise.all(
diff --git a/packages/repository/src/repositories/repository.ts b/packages/repository/src/repositories/repository.ts
index 6cb2cd507eb1..8d345fe7b83a 100644
--- a/packages/repository/src/repositories/repository.ts
+++ b/packages/repository/src/repositories/repository.ts
@@ -79,6 +79,15 @@ export interface CrudRepository<
    */
   create(dataObject: DataObject<T>, options?: Options): Promise<T>;
 
+  /**
+   * Update an existing entity or Create if it does not exist
+   * @param modelClass - The model class
+   * @param entity - The entity instance or data
+   * @param options - Options for the operation
+   * @returns A promise of the entity created
+   */
+  upsert(dataObject: DataObject<T>, options?: Options): Promise<T>;
+
   /**
    * Create all records
    * @param dataObjects - An array of data to be created
@@ -284,6 +293,12 @@ export class CrudRepositoryImpl<T extends Entity, ID>
     );
   }
 
+  upsert(entity: DataObject<T>, options?: Options): Promise<T> {
+    return this.toModel(
+      this.connector.upsert(this.entityClass, entity, options),
+    );
+  }
+
   createAll(entities: DataObject<T>[], options?: Options): Promise<T[]> {
     return this.toModels(
       this.connector.createAll!(this.entityClass, entities, options),
diff --git a/packages/rest-crud/src/crud-rest.controller.ts b/packages/rest-crud/src/crud-rest.controller.ts
index 0b8446712c9c..577f1eee8d12 100644
--- a/packages/rest-crud/src/crud-rest.controller.ts
+++ b/packages/rest-crud/src/crud-rest.controller.ts
@@ -105,6 +105,7 @@ export interface CrudRestControllerOptions {
    * Whether to generate readonly APIs
    */
   readonly?: boolean;
+  upsert?: boolean;
 }
 
 /**
@@ -276,14 +277,42 @@ export function defineCrudRestController<
     }
   }
 
+  @api({basePath: options.basePath, paths: {}})
+  class CrudRestControllerWithUpsertImpl extends CrudRestControllerImpl {
+    constructor(
+      public readonly repository: EntityCrudRepository<T, IdType, Relations>,
+    ) {
+      super(repository);
+    }
+    @post('/upsert', {
+      ...response.model(200, `${modelName} instance created`, modelCtor),
+    })
+    async upsert(
+      @body(modelCtor, {
+        title: `New${modelName}`,
+        exclude: modelCtor.getIdProperties() as (keyof T)[],
+      })
+      data: Omit<T, IdName>,
+    ): Promise<T> {
+      return this.repository.upsert(
+        // FIXME(bajtos) Improve repository API to support this use case
+        // with no explicit type-casts required
+        data as DataObject<T>,
+      );
+    }
+  }
+
   const controllerName = modelName + 'Controller';
   const defineNamedController = new Function(
     'controllerClass',
     `return class ${controllerName} extends controllerClass {}`,
   );
-  const controller = defineNamedController(
-    options.readonly ? ReadonlyRestControllerImpl : CrudRestControllerImpl,
-  );
+  let controllerImplementation = ReadonlyRestControllerImpl;
+  if (options.readonly) controllerImplementation = ReadonlyRestControllerImpl;
+  if (options.upsert)
+    controllerImplementation = CrudRestControllerWithUpsertImpl;
+
+  const controller = defineNamedController(controllerImplementation);
   assert.equal(controller.name, controllerName);
   return controller;
 }