diff --git a/components/brave_ads/core/internal/BUILD.gn b/components/brave_ads/core/internal/BUILD.gn
index 1146b08d50e1..90a0e47ac084 100644
--- a/components/brave_ads/core/internal/BUILD.gn
+++ b/components/brave_ads/core/internal/BUILD.gn
@@ -294,8 +294,6 @@ static_library("internal") {
     "ads.cc",
     "ads_client/ads_client_notifier.cc",
     "ads_client/ads_client_notifier_observer.cc",
-    "ads_client/ads_client_notifier_queue.cc",
-    "ads_client/ads_client_notifier_queue.h",
     "ads_client/ads_client_pref_provider.cc",
     "ads_client/ads_client_pref_provider.h",
     "ads_client/ads_client_util.cc",
@@ -413,6 +411,8 @@ static_library("internal") {
     "common/database/database_table_util.h",
     "common/database/database_transaction_util.cc",
     "common/database/database_transaction_util.h",
+    "common/functional/once_closure_queue.cc",
+    "common/functional/once_closure_queue.h",
     "common/instance_id.cc",
     "common/instance_id.h",
     "common/locale/locale_util.cc",
diff --git a/components/brave_ads/core/internal/ads_client/ads_client_notifier.cc b/components/brave_ads/core/internal/ads_client/ads_client_notifier.cc
index 6b3c220acbe3..2184123d5925 100644
--- a/components/brave_ads/core/internal/ads_client/ads_client_notifier.cc
+++ b/components/brave_ads/core/internal/ads_client/ads_client_notifier.cc
@@ -9,13 +9,13 @@
 #include <memory>
 
 #include "base/functional/bind.h"
-#include "brave/components/brave_ads/core/internal/ads_client/ads_client_notifier_queue.h"
+#include "brave/components/brave_ads/core/internal/common/functional/once_closure_queue.h"
 #include "url/gurl.h"
 
 namespace brave_ads {
 
 AdsClientNotifier::AdsClientNotifier()
-    : queue_(std::make_unique<AdsClientNotifierQueue>()) {}
+    : pending_task_queue_(std::make_unique<OnceClosureQueue>()) {}
 
 AdsClientNotifier::~AdsClientNotifier() = default;
 
@@ -34,12 +34,12 @@ void AdsClientNotifier::RemoveObserver(
 
 void AdsClientNotifier::NotifyPendingObservers() {
   should_queue_ = false;
-  queue_->Process();
+  pending_task_queue_->Process();
 }
 
 void AdsClientNotifier::NotifyDidInitializeAds() {
   if (should_queue_) {
-    return queue_->Add(
+    return pending_task_queue_->Add(
         base::BindOnce(&AdsClientNotifier::NotifyDidInitializeAds,
                        weak_factory_.GetWeakPtr()));
   }
@@ -53,7 +53,7 @@ void AdsClientNotifier::NotifyRewardsWalletDidUpdate(
     const std::string& payment_id,
     const std::string& recovery_seed_base64) {
   if (should_queue_) {
-    return queue_->Add(base::BindOnce(
+    return pending_task_queue_->Add(base::BindOnce(
         &AdsClientNotifier::NotifyRewardsWalletDidUpdate,
         weak_factory_.GetWeakPtr(), payment_id, recovery_seed_base64));
   }
@@ -65,8 +65,9 @@ void AdsClientNotifier::NotifyRewardsWalletDidUpdate(
 
 void AdsClientNotifier::NotifyLocaleDidChange(const std::string& locale) {
   if (should_queue_) {
-    return queue_->Add(base::BindOnce(&AdsClientNotifier::NotifyLocaleDidChange,
-                                      weak_factory_.GetWeakPtr(), locale));
+    return pending_task_queue_->Add(
+        base::BindOnce(&AdsClientNotifier::NotifyLocaleDidChange,
+                       weak_factory_.GetWeakPtr(), locale));
   }
 
   for (auto& observer : observers_) {
@@ -76,8 +77,9 @@ void AdsClientNotifier::NotifyLocaleDidChange(const std::string& locale) {
 
 void AdsClientNotifier::NotifyPrefDidChange(const std::string& path) {
   if (should_queue_) {
-    return queue_->Add(base::BindOnce(&AdsClientNotifier::NotifyPrefDidChange,
-                                      weak_factory_.GetWeakPtr(), path));
+    return pending_task_queue_->Add(
+        base::BindOnce(&AdsClientNotifier::NotifyPrefDidChange,
+                       weak_factory_.GetWeakPtr(), path));
   }
 
   for (auto& observer : observers_) {
@@ -89,7 +91,7 @@ void AdsClientNotifier::NotifyResourceComponentDidChange(
     const std::string& manifest_version,
     const std::string& id) {
   if (should_queue_) {
-    return queue_->Add(
+    return pending_task_queue_->Add(
         base::BindOnce(&AdsClientNotifier::NotifyResourceComponentDidChange,
                        weak_factory_.GetWeakPtr(), manifest_version, id));
   }
@@ -102,7 +104,7 @@ void AdsClientNotifier::NotifyResourceComponentDidChange(
 void AdsClientNotifier::NotifyDidUnregisterResourceComponent(
     const std::string& id) {
   if (should_queue_) {
-    return queue_->Add(
+    return pending_task_queue_->Add(
         base::BindOnce(&AdsClientNotifier::NotifyDidUnregisterResourceComponent,
                        weak_factory_.GetWeakPtr(), id));
   }
@@ -117,7 +119,7 @@ void AdsClientNotifier::NotifyTabTextContentDidChange(
     const std::vector<GURL>& redirect_chain,
     const std::string& text) {
   if (should_queue_) {
-    return queue_->Add(base::BindOnce(
+    return pending_task_queue_->Add(base::BindOnce(
         &AdsClientNotifier::NotifyTabTextContentDidChange,
         weak_factory_.GetWeakPtr(), tab_id, redirect_chain, text));
   }
@@ -132,7 +134,7 @@ void AdsClientNotifier::NotifyTabHtmlContentDidChange(
     const std::vector<GURL>& redirect_chain,
     const std::string& html) {
   if (should_queue_) {
-    return queue_->Add(base::BindOnce(
+    return pending_task_queue_->Add(base::BindOnce(
         &AdsClientNotifier::NotifyTabHtmlContentDidChange,
         weak_factory_.GetWeakPtr(), tab_id, redirect_chain, html));
   }
@@ -144,7 +146,7 @@ void AdsClientNotifier::NotifyTabHtmlContentDidChange(
 
 void AdsClientNotifier::NotifyTabDidStartPlayingMedia(const int32_t tab_id) {
   if (should_queue_) {
-    return queue_->Add(
+    return pending_task_queue_->Add(
         base::BindOnce(&AdsClientNotifier::NotifyTabDidStartPlayingMedia,
                        weak_factory_.GetWeakPtr(), tab_id));
   }
@@ -156,7 +158,7 @@ void AdsClientNotifier::NotifyTabDidStartPlayingMedia(const int32_t tab_id) {
 
 void AdsClientNotifier::NotifyTabDidStopPlayingMedia(const int32_t tab_id) {
   if (should_queue_) {
-    return queue_->Add(
+    return pending_task_queue_->Add(
         base::BindOnce(&AdsClientNotifier::NotifyTabDidStopPlayingMedia,
                        weak_factory_.GetWeakPtr(), tab_id));
   }
@@ -173,7 +175,7 @@ void AdsClientNotifier::NotifyTabDidChange(
     const bool is_restoring,
     const bool is_visible) {
   if (should_queue_) {
-    return queue_->Add(base::BindOnce(
+    return pending_task_queue_->Add(base::BindOnce(
         &AdsClientNotifier::NotifyTabDidChange, weak_factory_.GetWeakPtr(),
         tab_id, redirect_chain, is_new_navigation, is_restoring, is_visible));
   }
@@ -199,8 +201,9 @@ void AdsClientNotifier::NotifyTabDidLoad(const int32_t tab_id,
 
 void AdsClientNotifier::NotifyDidCloseTab(const int32_t tab_id) {
   if (should_queue_) {
-    return queue_->Add(base::BindOnce(&AdsClientNotifier::NotifyDidCloseTab,
-                                      weak_factory_.GetWeakPtr(), tab_id));
+    return pending_task_queue_->Add(
+        base::BindOnce(&AdsClientNotifier::NotifyDidCloseTab,
+                       weak_factory_.GetWeakPtr(), tab_id));
   }
 
   for (auto& observer : observers_) {
@@ -211,7 +214,7 @@ void AdsClientNotifier::NotifyDidCloseTab(const int32_t tab_id) {
 void AdsClientNotifier::NotifyUserGestureEventTriggered(
     const int32_t page_transition_type) {
   if (should_queue_) {
-    return queue_->Add(
+    return pending_task_queue_->Add(
         base::BindOnce(&AdsClientNotifier::NotifyUserGestureEventTriggered,
                        weak_factory_.GetWeakPtr(), page_transition_type));
   }
@@ -223,7 +226,7 @@ void AdsClientNotifier::NotifyUserGestureEventTriggered(
 
 void AdsClientNotifier::NotifyUserDidBecomeIdle() {
   if (should_queue_) {
-    return queue_->Add(
+    return pending_task_queue_->Add(
         base::BindOnce(&AdsClientNotifier::NotifyUserDidBecomeIdle,
                        weak_factory_.GetWeakPtr()));
   }
@@ -237,7 +240,7 @@ void AdsClientNotifier::NotifyUserDidBecomeActive(
     const base::TimeDelta idle_time,
     const bool screen_was_locked) {
   if (should_queue_) {
-    return queue_->Add(base::BindOnce(
+    return pending_task_queue_->Add(base::BindOnce(
         &AdsClientNotifier::NotifyUserDidBecomeActive,
         weak_factory_.GetWeakPtr(), idle_time, screen_was_locked));
   }
@@ -249,7 +252,7 @@ void AdsClientNotifier::NotifyUserDidBecomeActive(
 
 void AdsClientNotifier::NotifyBrowserDidEnterForeground() {
   if (should_queue_) {
-    return queue_->Add(
+    return pending_task_queue_->Add(
         base::BindOnce(&AdsClientNotifier::NotifyBrowserDidEnterForeground,
                        weak_factory_.GetWeakPtr()));
   }
@@ -261,7 +264,7 @@ void AdsClientNotifier::NotifyBrowserDidEnterForeground() {
 
 void AdsClientNotifier::NotifyBrowserDidEnterBackground() {
   if (should_queue_) {
-    return queue_->Add(
+    return pending_task_queue_->Add(
         base::BindOnce(&AdsClientNotifier::NotifyBrowserDidEnterBackground,
                        weak_factory_.GetWeakPtr()));
   }
@@ -273,7 +276,7 @@ void AdsClientNotifier::NotifyBrowserDidEnterBackground() {
 
 void AdsClientNotifier::NotifyBrowserDidBecomeActive() {
   if (should_queue_) {
-    return queue_->Add(
+    return pending_task_queue_->Add(
         base::BindOnce(&AdsClientNotifier::NotifyBrowserDidBecomeActive,
                        weak_factory_.GetWeakPtr()));
   }
@@ -285,7 +288,7 @@ void AdsClientNotifier::NotifyBrowserDidBecomeActive() {
 
 void AdsClientNotifier::NotifyBrowserDidResignActive() {
   if (should_queue_) {
-    return queue_->Add(
+    return pending_task_queue_->Add(
         base::BindOnce(&AdsClientNotifier::NotifyBrowserDidResignActive,
                        weak_factory_.GetWeakPtr()));
   }
@@ -297,7 +300,7 @@ void AdsClientNotifier::NotifyBrowserDidResignActive() {
 
 void AdsClientNotifier::NotifyDidSolveAdaptiveCaptcha() {
   if (should_queue_) {
-    return queue_->Add(
+    return pending_task_queue_->Add(
         base::BindOnce(&AdsClientNotifier::NotifyDidSolveAdaptiveCaptcha,
                        weak_factory_.GetWeakPtr()));
   }
diff --git a/components/brave_ads/core/internal/ads_client/ads_client_notifier_for_testing.cc b/components/brave_ads/core/internal/ads_client/ads_client_notifier_for_testing.cc
index 69f62ad50835..9f77e7c6d9e2 100644
--- a/components/brave_ads/core/internal/ads_client/ads_client_notifier_for_testing.cc
+++ b/components/brave_ads/core/internal/ads_client/ads_client_notifier_for_testing.cc
@@ -9,6 +9,12 @@
 
 namespace brave_ads {
 
+void AdsClientNotifierForTesting::NotifyPendingObservers() {
+  AdsClientNotifier::NotifyPendingObservers();
+
+  RunTaskEnvironmentUntilIdle();
+}
+
 void AdsClientNotifierForTesting::NotifyDidInitializeAds() {
   AdsClientNotifier::NotifyDidInitializeAds();
 
diff --git a/components/brave_ads/core/internal/ads_client/ads_client_notifier_for_testing.h b/components/brave_ads/core/internal/ads_client/ads_client_notifier_for_testing.h
index 0482cdda3671..4078d79b38c0 100644
--- a/components/brave_ads/core/internal/ads_client/ads_client_notifier_for_testing.h
+++ b/components/brave_ads/core/internal/ads_client/ads_client_notifier_for_testing.h
@@ -32,6 +32,8 @@ class AdsClientNotifierForTesting : public AdsClientNotifier {
     task_environment_ = task_environment;
   }
 
+  void NotifyPendingObservers() override;
+
   void NotifyDidInitializeAds() override;
 
   void NotifyLocaleDidChange(const std::string& locale) override;
diff --git a/components/brave_ads/core/internal/ads_client/ads_client_notifier_queue.h b/components/brave_ads/core/internal/ads_client/ads_client_notifier_queue.h
deleted file mode 100644
index 2c8b735ad33f..000000000000
--- a/components/brave_ads/core/internal/ads_client/ads_client_notifier_queue.h
+++ /dev/null
@@ -1,35 +0,0 @@
-/* Copyright (c) 2023 The Brave Authors. All rights reserved.
- * This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this file,
- * You can obtain one at https://mozilla.org/MPL/2.0/. */
-
-#ifndef BRAVE_COMPONENTS_BRAVE_ADS_CORE_INTERNAL_ADS_CLIENT_ADS_CLIENT_NOTIFIER_QUEUE_H_
-#define BRAVE_COMPONENTS_BRAVE_ADS_CORE_INTERNAL_ADS_CLIENT_ADS_CLIENT_NOTIFIER_QUEUE_H_
-
-#include "base/containers/queue.h"
-#include "base/functional/callback.h"
-
-namespace brave_ads {
-
-class AdsClientNotifierQueue final {
- public:
-  AdsClientNotifierQueue();
-
-  AdsClientNotifierQueue(const AdsClientNotifierQueue&) = delete;
-  AdsClientNotifierQueue& operator=(const AdsClientNotifierQueue&) = delete;
-
-  AdsClientNotifierQueue(AdsClientNotifierQueue&&) noexcept = delete;
-  AdsClientNotifierQueue& operator=(AdsClientNotifierQueue&&) noexcept = delete;
-
-  ~AdsClientNotifierQueue();
-
-  void Add(base::OnceClosure notifier);
-  void Process();
-
- private:
-  base::queue<base::OnceClosure> queue_;
-};
-
-}  // namespace brave_ads
-
-#endif  // BRAVE_COMPONENTS_BRAVE_ADS_CORE_INTERNAL_ADS_CLIENT_ADS_CLIENT_NOTIFIER_QUEUE_H_
diff --git a/components/brave_ads/core/internal/ads_client/ads_client_notifier_unittest.cc b/components/brave_ads/core/internal/ads_client/ads_client_notifier_unittest.cc
index 3c9051f17c20..bc1c9ed7ac53 100644
--- a/components/brave_ads/core/internal/ads_client/ads_client_notifier_unittest.cc
+++ b/components/brave_ads/core/internal/ads_client/ads_client_notifier_unittest.cc
@@ -177,7 +177,6 @@ class BraveAdsAdsClientNotifierTest : public ::testing::Test {
 
 TEST_F(BraveAdsAdsClientNotifierTest, FireQueuedAdsClientNotifications) {
   // Arrange
-  ads_client_notifier_.set_should_queue_for_testing(true);
 
   // Act & Assert
   ExpectAdsClientNotifierCallCount(0);
@@ -198,7 +197,6 @@ TEST_F(
     BraveAdsAdsClientNotifierTest,
     DoNotFireQueuedAdsClientNotificationsIfNotifyPendingObserversIsNotCalled) {
   // Arrange
-  ads_client_notifier_.set_should_queue_for_testing(true);
 
   // Act & Assert
   ExpectAdsClientNotifierCallCount(0);
@@ -206,9 +204,9 @@ TEST_F(
 }
 
 TEST_F(BraveAdsAdsClientNotifierTest,
-       FireAdsClientNotificationsImmediatelyIfNotQueued) {
+       FireAdsClientNotificationsImmediatelyIfNotifyPendingObserversWasCalled) {
   // Arrange
-  ads_client_notifier_.set_should_queue_for_testing(false);
+  ads_client_notifier_.NotifyPendingObservers();
 
   // Act & Assert
   ExpectAdsClientNotifierCallCount(1);
diff --git a/components/brave_ads/core/internal/ads_impl.cc b/components/brave_ads/core/internal/ads_impl.cc
index 3696821c0259..0cf4ade8537a 100644
--- a/components/brave_ads/core/internal/ads_impl.cc
+++ b/components/brave_ads/core/internal/ads_impl.cc
@@ -25,6 +25,7 @@
 #include "brave/components/brave_ads/core/internal/legacy_migration/confirmations/legacy_confirmation_migration.h"
 #include "brave/components/brave_ads/core/internal/user_engagement/ad_events/ad_events.h"
 #include "brave/components/brave_ads/core/public/ad_units/notification_ad/notification_ad_info.h"
+#include "brave/components/brave_ads/core/public/ad_units/notification_ad/notification_ad_value_util.h"
 #include "brave/components/brave_ads/core/public/ads_client/ads_client.h"
 
 namespace brave_ads {
@@ -86,7 +87,9 @@ void AdsImpl::Shutdown(ShutdownCallback callback) {
   if (!is_initialized_) {
     BLOG(0, "Shutdown failed as not initialized");
 
-    return std::move(callback).Run(/*success=*/false);
+    pending_task_queue_.Add(base::BindOnce(
+        &AdsImpl::Shutdown, weak_factory_.GetWeakPtr(), std::move(callback)));
+    return;
   }
 
   NotificationAdManager::GetInstance().RemoveAll(/*should_close=*/true);
@@ -96,7 +99,10 @@ void AdsImpl::Shutdown(ShutdownCallback callback) {
 
 void AdsImpl::GetDiagnostics(GetDiagnosticsCallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(/*diagnostics=*/std::nullopt);
+    pending_task_queue_.Add(base::BindOnce(&AdsImpl::GetDiagnostics,
+                                           weak_factory_.GetWeakPtr(),
+                                           std::move(callback)));
+    return;
   }
 
   DiagnosticManager::GetInstance().GetDiagnostics(std::move(callback));
@@ -104,7 +110,10 @@ void AdsImpl::GetDiagnostics(GetDiagnosticsCallback callback) {
 
 void AdsImpl::GetStatementOfAccounts(GetStatementOfAccountsCallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(/*statement=*/nullptr);
+    pending_task_queue_.Add(base::BindOnce(&AdsImpl::GetStatementOfAccounts,
+                                           weak_factory_.GetWeakPtr(),
+                                           std::move(callback)));
+    return;
   }
 
   GetAccount().GetStatement(std::move(callback));
@@ -114,7 +123,10 @@ void AdsImpl::MaybeServeInlineContentAd(
     const std::string& dimensions,
     MaybeServeInlineContentAdCallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(dimensions, /*ad=*/std::nullopt);
+    pending_task_queue_.Add(base::BindOnce(&AdsImpl::MaybeServeInlineContentAd,
+                                           weak_factory_.GetWeakPtr(),
+                                           dimensions, std::move(callback)));
+    return;
   }
 
   GetAdHandler().MaybeServeInlineContentAd(dimensions, std::move(callback));
@@ -126,7 +138,11 @@ void AdsImpl::TriggerInlineContentAdEvent(
     const mojom::InlineContentAdEventType mojom_ad_event_type,
     TriggerAdEventCallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(/*success=*/false);
+    pending_task_queue_.Add(base::BindOnce(
+        &AdsImpl::TriggerInlineContentAdEvent, weak_factory_.GetWeakPtr(),
+        placement_id, creative_instance_id, mojom_ad_event_type,
+        std::move(callback)));
+    return;
   }
 
   GetAdHandler().TriggerInlineContentAdEvent(placement_id, creative_instance_id,
@@ -136,7 +152,10 @@ void AdsImpl::TriggerInlineContentAdEvent(
 
 void AdsImpl::MaybeServeNewTabPageAd(MaybeServeNewTabPageAdCallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(/*ad=*/std::nullopt);
+    pending_task_queue_.Add(base::BindOnce(&AdsImpl::MaybeServeNewTabPageAd,
+                                           weak_factory_.GetWeakPtr(),
+                                           std::move(callback)));
+    return;
   }
 
   GetAdHandler().MaybeServeNewTabPageAd(std::move(callback));
@@ -148,7 +167,11 @@ void AdsImpl::TriggerNewTabPageAdEvent(
     const mojom::NewTabPageAdEventType mojom_ad_event_type,
     TriggerAdEventCallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(/*success=*/false);
+    pending_task_queue_.Add(base::BindOnce(
+        &AdsImpl::TriggerNewTabPageAdEvent, weak_factory_.GetWeakPtr(),
+        placement_id, creative_instance_id, mojom_ad_event_type,
+        std::move(callback)));
+    return;
   }
 
   GetAdHandler().TriggerNewTabPageAdEvent(placement_id, creative_instance_id,
@@ -156,10 +179,18 @@ void AdsImpl::TriggerNewTabPageAdEvent(
                                           std::move(callback));
 }
 
-std::optional<NotificationAdInfo> AdsImpl::MaybeGetNotificationAd(
-    const std::string& placement_id) {
-  return NotificationAdManager::GetInstance().MaybeGetForPlacementId(
-      placement_id);
+void AdsImpl::MaybeGetNotificationAd(const std::string& placement_id,
+                                     MaybeGetNotificationAdCallback callback) {
+  if (!is_initialized_) {
+    pending_task_queue_.Add(base::BindOnce(&AdsImpl::MaybeGetNotificationAd,
+                                           weak_factory_.GetWeakPtr(),
+                                           placement_id, std::move(callback)));
+    return;
+  }
+
+  std::move(callback).Run(
+      NotificationAdManager::GetInstance().MaybeGetForPlacementId(
+          placement_id));
 }
 
 void AdsImpl::TriggerNotificationAdEvent(
@@ -167,7 +198,10 @@ void AdsImpl::TriggerNotificationAdEvent(
     const mojom::NotificationAdEventType mojom_ad_event_type,
     TriggerAdEventCallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(/*success=*/false);
+    pending_task_queue_.Add(base::BindOnce(
+        &AdsImpl::TriggerNotificationAdEvent, weak_factory_.GetWeakPtr(),
+        placement_id, mojom_ad_event_type, std::move(callback)));
+    return;
   }
 
   GetAdHandler().TriggerNotificationAdEvent(placement_id, mojom_ad_event_type,
@@ -180,7 +214,11 @@ void AdsImpl::TriggerPromotedContentAdEvent(
     const mojom::PromotedContentAdEventType mojom_ad_event_type,
     TriggerAdEventCallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(/*success=*/false);
+    pending_task_queue_.Add(base::BindOnce(
+        &AdsImpl::TriggerPromotedContentAdEvent, weak_factory_.GetWeakPtr(),
+        placement_id, creative_instance_id, mojom_ad_event_type,
+        std::move(callback)));
+    return;
   }
 
   GetAdHandler().TriggerPromotedContentAdEvent(
@@ -193,7 +231,11 @@ void AdsImpl::TriggerSearchResultAdEvent(
     const mojom::SearchResultAdEventType mojom_ad_event_type,
     TriggerAdEventCallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(/*success=*/false);
+    pending_task_queue_.Add(
+        base::BindOnce(&AdsImpl::TriggerSearchResultAdEvent,
+                       weak_factory_.GetWeakPtr(), std::move(mojom_creative_ad),
+                       mojom_ad_event_type, std::move(callback)));
+    return;
   }
 
   GetAdHandler().TriggerSearchResultAdEvent(
@@ -204,7 +246,10 @@ void AdsImpl::PurgeOrphanedAdEventsForType(
     const mojom::AdType mojom_ad_type,
     PurgeOrphanedAdEventsForTypeCallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(/*success=*/false);
+    pending_task_queue_.Add(base::BindOnce(
+        &AdsImpl::PurgeOrphanedAdEventsForType, weak_factory_.GetWeakPtr(),
+        mojom_ad_type, std::move(callback)));
+    return;
   }
 
   PurgeOrphanedAdEvents(
@@ -229,7 +274,10 @@ void AdsImpl::GetAdHistory(const base::Time from_time,
                            const base::Time to_time,
                            GetAdHistoryForUICallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(/*ad_history=*/std::nullopt);
+    pending_task_queue_.Add(
+        base::BindOnce(&AdsImpl::GetAdHistory, weak_factory_.GetWeakPtr(),
+                       from_time, to_time, std::move(callback)));
+    return;
   }
 
   AdHistoryManager::GetForUI(from_time, to_time, std::move(callback));
@@ -238,7 +286,10 @@ void AdsImpl::GetAdHistory(const base::Time from_time,
 void AdsImpl::ToggleLikeAd(mojom::ReactionInfoPtr mojom_reaction,
                            ToggleReactionCallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(/*success=*/false);
+    pending_task_queue_.Add(
+        base::BindOnce(&AdsImpl::ToggleLikeAd, weak_factory_.GetWeakPtr(),
+                       std::move(mojom_reaction), std::move(callback)));
+    return;
   }
 
   GetReactions().ToggleLikeAd(std::move(mojom_reaction), std::move(callback));
@@ -247,7 +298,10 @@ void AdsImpl::ToggleLikeAd(mojom::ReactionInfoPtr mojom_reaction,
 void AdsImpl::ToggleDislikeAd(mojom::ReactionInfoPtr mojom_reaction,
                               ToggleReactionCallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(/*success=*/false);
+    pending_task_queue_.Add(
+        base::BindOnce(&AdsImpl::ToggleDislikeAd, weak_factory_.GetWeakPtr(),
+                       std::move(mojom_reaction), std::move(callback)));
+    return;
   }
 
   GetReactions().ToggleDislikeAd(std::move(mojom_reaction),
@@ -257,7 +311,10 @@ void AdsImpl::ToggleDislikeAd(mojom::ReactionInfoPtr mojom_reaction,
 void AdsImpl::ToggleLikeSegment(mojom::ReactionInfoPtr mojom_reaction,
                                 ToggleReactionCallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(/*success=*/false);
+    pending_task_queue_.Add(
+        base::BindOnce(&AdsImpl::ToggleLikeSegment, weak_factory_.GetWeakPtr(),
+                       std::move(mojom_reaction), std::move(callback)));
+    return;
   }
 
   GetReactions().ToggleLikeSegment(std::move(mojom_reaction),
@@ -267,7 +324,10 @@ void AdsImpl::ToggleLikeSegment(mojom::ReactionInfoPtr mojom_reaction,
 void AdsImpl::ToggleDislikeSegment(mojom::ReactionInfoPtr mojom_reaction,
                                    ToggleReactionCallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(/*success=*/false);
+    pending_task_queue_.Add(base::BindOnce(
+        &AdsImpl::ToggleDislikeSegment, weak_factory_.GetWeakPtr(),
+        std::move(mojom_reaction), std::move(callback)));
+    return;
   }
 
   GetReactions().ToggleDislikeSegment(std::move(mojom_reaction),
@@ -277,7 +337,10 @@ void AdsImpl::ToggleDislikeSegment(mojom::ReactionInfoPtr mojom_reaction,
 void AdsImpl::ToggleSaveAd(mojom::ReactionInfoPtr mojom_reaction,
                            ToggleReactionCallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(/*success=*/false);
+    pending_task_queue_.Add(
+        base::BindOnce(&AdsImpl::ToggleSaveAd, weak_factory_.GetWeakPtr(),
+                       std::move(mojom_reaction), std::move(callback)));
+    return;
   }
 
   GetReactions().ToggleSaveAd(std::move(mojom_reaction), std::move(callback));
@@ -286,7 +349,10 @@ void AdsImpl::ToggleSaveAd(mojom::ReactionInfoPtr mojom_reaction,
 void AdsImpl::ToggleMarkAdAsInappropriate(mojom::ReactionInfoPtr mojom_reaction,
                                           ToggleReactionCallback callback) {
   if (!is_initialized_) {
-    return std::move(callback).Run(/*success=*/false);
+    pending_task_queue_.Add(base::BindOnce(
+        &AdsImpl::ToggleMarkAdAsInappropriate, weak_factory_.GetWeakPtr(),
+        std::move(mojom_reaction), std::move(callback)));
+    return;
   }
 
   GetReactions().ToggleMarkAdAsInappropriate(std::move(mojom_reaction),
@@ -329,6 +395,8 @@ void AdsImpl::SuccessfullyInitialized(mojom::WalletInfoPtr mojom_wallet,
 
   GetAdsClient()->NotifyPendingObservers();
 
+  pending_task_queue_.Process();
+
   std::move(callback).Run(/*success=*/true);
 }
 
diff --git a/components/brave_ads/core/internal/ads_impl.h b/components/brave_ads/core/internal/ads_impl.h
index 30c8b5943114..619ea661f6f7 100644
--- a/components/brave_ads/core/internal/ads_impl.h
+++ b/components/brave_ads/core/internal/ads_impl.h
@@ -7,12 +7,12 @@
 #define BRAVE_COMPONENTS_BRAVE_ADS_CORE_INTERNAL_ADS_IMPL_H_
 
 #include <memory>
-#include <optional>
 #include <string>
 
 #include "base/memory/weak_ptr.h"
 #include "brave/components/brave_ads/browser/ads_service_callback.h"
 #include "brave/components/brave_ads/core/internal/account/tokens/token_generator_interface.h"
+#include "brave/components/brave_ads/core/internal/common/functional/once_closure_queue.h"
 #include "brave/components/brave_ads/core/internal/global_state/global_state.h"
 #include "brave/components/brave_ads/core/mojom/brave_ads.mojom-forward.h"
 #include "brave/components/brave_ads/core/public/ads.h"
@@ -24,8 +24,6 @@ class Time;
 
 namespace brave_ads {
 
-struct NotificationAdInfo;
-
 namespace database {
 class Maintenance;
 }  // namespace database
@@ -74,8 +72,8 @@ class AdsImpl final : public Ads {
       mojom::NewTabPageAdEventType mojom_ad_event_type,
       TriggerAdEventCallback callback) override;
 
-  std::optional<NotificationAdInfo> MaybeGetNotificationAd(
-      const std::string& placement_id) override;
+  void MaybeGetNotificationAd(const std::string& placement_id,
+                              MaybeGetNotificationAdCallback callback) override;
   void TriggerNotificationAdEvent(
       const std::string& placement_id,
       mojom::NotificationAdEventType mojom_ad_event_type,
@@ -143,6 +141,8 @@ class AdsImpl final : public Ads {
   // state.
   GlobalState global_state_;
 
+  OnceClosureQueue pending_task_queue_;
+
   // Handles database maintenance tasks, such as purging.
   std::unique_ptr<database::Maintenance> database_maintenance_;
 
diff --git a/components/brave_ads/core/internal/ads_client/ads_client_notifier_queue.cc b/components/brave_ads/core/internal/common/functional/once_closure_queue.cc
similarity index 55%
rename from components/brave_ads/core/internal/ads_client/ads_client_notifier_queue.cc
rename to components/brave_ads/core/internal/common/functional/once_closure_queue.cc
index af0de6884cf3..5c987a3586b4 100644
--- a/components/brave_ads/core/internal/ads_client/ads_client_notifier_queue.cc
+++ b/components/brave_ads/core/internal/common/functional/once_closure_queue.cc
@@ -3,21 +3,21 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this file,
  * You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-#include "brave/components/brave_ads/core/internal/ads_client/ads_client_notifier_queue.h"
+#include "brave/components/brave_ads/core/internal/common/functional/once_closure_queue.h"
 
 #include <utility>
 
 namespace brave_ads {
 
-AdsClientNotifierQueue::AdsClientNotifierQueue() = default;
+OnceClosureQueue::OnceClosureQueue() = default;
 
-AdsClientNotifierQueue::~AdsClientNotifierQueue() = default;
+OnceClosureQueue::~OnceClosureQueue() = default;
 
-void AdsClientNotifierQueue::Add(base::OnceClosure notifier) {
-  queue_.push(std::move(notifier));
+void OnceClosureQueue::Add(base::OnceClosure closure) {
+  queue_.push(std::move(closure));
 }
 
-void AdsClientNotifierQueue::Process() {
+void OnceClosureQueue::Process() {
   while (!queue_.empty()) {
     std::move(queue_.front()).Run();
     queue_.pop();
diff --git a/components/brave_ads/core/internal/common/functional/once_closure_queue.h b/components/brave_ads/core/internal/common/functional/once_closure_queue.h
new file mode 100644
index 000000000000..33c2da911e5a
--- /dev/null
+++ b/components/brave_ads/core/internal/common/functional/once_closure_queue.h
@@ -0,0 +1,35 @@
+/* Copyright (c) 2023 The Brave Authors. All rights reserved.
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_COMPONENTS_BRAVE_ADS_CORE_INTERNAL_COMMON_FUNCTIONAL_ONCE_CLOSURE_QUEUE_H_
+#define BRAVE_COMPONENTS_BRAVE_ADS_CORE_INTERNAL_COMMON_FUNCTIONAL_ONCE_CLOSURE_QUEUE_H_
+
+#include "base/containers/queue.h"
+#include "base/functional/callback.h"
+
+namespace brave_ads {
+
+class OnceClosureQueue final {
+ public:
+  OnceClosureQueue();
+
+  OnceClosureQueue(const OnceClosureQueue&) = delete;
+  OnceClosureQueue& operator=(const OnceClosureQueue&) = delete;
+
+  OnceClosureQueue(OnceClosureQueue&&) noexcept = delete;
+  OnceClosureQueue& operator=(OnceClosureQueue&&) noexcept = delete;
+
+  ~OnceClosureQueue();
+
+  void Add(base::OnceClosure closure);
+  void Process();
+
+ private:
+  base::queue<base::OnceClosure> queue_;
+};
+
+}  // namespace brave_ads
+
+#endif  // BRAVE_COMPONENTS_BRAVE_ADS_CORE_INTERNAL_COMMON_FUNCTIONAL_ONCE_CLOSURE_QUEUE_H_
diff --git a/components/brave_ads/core/internal/common/test/test_base.cc b/components/brave_ads/core/internal/common/test/test_base.cc
index bf325dc985d9..227c1abce1eb 100644
--- a/components/brave_ads/core/internal/common/test/test_base.cc
+++ b/components/brave_ads/core/internal/common/test/test_base.cc
@@ -323,6 +323,8 @@ void TestBase::SetUpIntegrationTestCallback(const bool success) {
   NotifyBrowserDidBecomeActive();
 
   NotifyDidInitializeAds();
+
+  NotifyPendingObservers();
 }
 
 void TestBase::SetUpUnitTest() {
@@ -337,6 +339,8 @@ void TestBase::SetUpUnitTest() {
   Mock();
 
   MockDefaultAdsServiceState();
+
+  NotifyPendingObservers();
 }
 
 }  // namespace brave_ads::test
diff --git a/components/brave_ads/core/public/ads.h b/components/brave_ads/core/public/ads.h
index 182306320f49..9da26b8e1f38 100644
--- a/components/brave_ads/core/public/ads.h
+++ b/components/brave_ads/core/public/ads.h
@@ -109,10 +109,11 @@ class ADS_EXPORT Ads {
       mojom::NewTabPageAdEventType mojom_ad_event_type,
       TriggerAdEventCallback callback) = 0;
 
-  // Called to get the notification ad specified by `placement_id`. Returns
-  // `NotificationAdInfo` containing the info of the ad.
-  virtual std::optional<NotificationAdInfo> MaybeGetNotificationAd(
-      const std::string& placement_id) = 0;
+  // Called to get the notification ad specified by `placement_id`. The callback
+  // takes one argument - `NotificationAdInfo` containing the info of the ad.
+  virtual void MaybeGetNotificationAd(
+      const std::string& placement_id,
+      MaybeGetNotificationAdCallback callback) = 0;
 
   // Called when a user views or interacts with a notification ad or the ad
   // notification times out to trigger a `mojom_ad_event_type` event for the
diff --git a/components/brave_ads/core/public/ads_callback.h b/components/brave_ads/core/public/ads_callback.h
index 2033f6c7190c..4e82c54a5e69 100644
--- a/components/brave_ads/core/public/ads_callback.h
+++ b/components/brave_ads/core/public/ads_callback.h
@@ -14,6 +14,7 @@
 #include "brave/components/brave_ads/core/mojom/brave_ads.mojom-forward.h"
 #include "brave/components/brave_ads/core/public/ad_units/inline_content_ad/inline_content_ad_info.h"
 #include "brave/components/brave_ads/core/public/ad_units/new_tab_page_ad/new_tab_page_ad_info.h"
+#include "brave/components/brave_ads/core/public/ad_units/notification_ad/notification_ad_info.h"
 #include "brave/components/brave_ads/core/public/history/ad_history_item_info.h"
 
 namespace brave_ads {
@@ -34,6 +35,9 @@ using MaybeServeInlineContentAdCallback =
     base::OnceCallback<void(const std::string& dimensions,
                             const std::optional<InlineContentAdInfo>& ad)>;
 
+using MaybeGetNotificationAdCallback =
+    base::OnceCallback<void(const std::optional<NotificationAdInfo>& ad)>;
+
 using TriggerAdEventCallback = base::OnceCallback<void(bool success)>;
 
 using PurgeOrphanedAdEventsForTypeCallback =
diff --git a/components/brave_ads/core/public/ads_client/ads_client.h b/components/brave_ads/core/public/ads_client/ads_client.h
index b22e43a7d77f..e1962fc9d53d 100644
--- a/components/brave_ads/core/public/ads_client/ads_client.h
+++ b/components/brave_ads/core/public/ads_client/ads_client.h
@@ -32,7 +32,7 @@ class ADS_EXPORT AdsClient {
   // Called to remove an ads client observer.
   virtual void RemoveObserver(AdsClientNotifierObserver* observer) = 0;
 
-  // Called to bind pending ads client observers.
+  // Called to fire all pending observer events.
   virtual void NotifyPendingObservers() = 0;
 
   // Returns `true` if there is an available network connection.
diff --git a/components/brave_ads/core/public/ads_client/ads_client_notifier.h b/components/brave_ads/core/public/ads_client/ads_client_notifier.h
index 156526fc2864..264e6d1e2ba4 100644
--- a/components/brave_ads/core/public/ads_client/ads_client_notifier.h
+++ b/components/brave_ads/core/public/ads_client/ads_client_notifier.h
@@ -19,7 +19,7 @@ class GURL;
 
 namespace brave_ads {
 
-class AdsClientNotifierQueue;
+class OnceClosureQueue;
 
 class AdsClientNotifier {
  public:
@@ -33,10 +33,6 @@ class AdsClientNotifier {
 
   virtual ~AdsClientNotifier();
 
-  void set_should_queue_for_testing(bool should_queue) {
-    should_queue_ = should_queue;
-  }
-
   void AddObserver(AdsClientNotifierObserver* observer);
   void RemoveObserver(AdsClientNotifierObserver* observer);
 
@@ -151,13 +147,9 @@ class AdsClientNotifier {
  private:
   base::ObserverList<AdsClientNotifierObserver> observers_;
 
-  std::unique_ptr<AdsClientNotifierQueue> queue_;
+  std::unique_ptr<OnceClosureQueue> pending_task_queue_;
 
-#if BUILDFLAG(IS_IOS)
   bool should_queue_ = true;
-#else
-  bool should_queue_ = false;
-#endif  // BUILDFLAG(IS_IOS)
 
   base::WeakPtrFactory<AdsClientNotifier> weak_factory_{this};
 };
diff --git a/components/services/bat_ads/bat_ads_client_mojo_bridge.cc b/components/services/bat_ads/bat_ads_client_mojo_bridge.cc
index 79233c8a79eb..626c7a7c1587 100644
--- a/components/services/bat_ads/bat_ads_client_mojo_bridge.cc
+++ b/components/services/bat_ads/bat_ads_client_mojo_bridge.cc
@@ -40,7 +40,7 @@ void BatAdsClientMojoBridge::RemoveObserver(
 }
 
 void BatAdsClientMojoBridge::NotifyPendingObservers() {
-  bat_ads_client_notifier_impl_.BindReceiver();
+  bat_ads_client_notifier_impl_.NotifyPendingObservers();
 }
 
 bool BatAdsClientMojoBridge::CanShowNotificationAdsWhileBrowserIsBackgrounded()
diff --git a/components/services/bat_ads/bat_ads_client_notifier_impl.cc b/components/services/bat_ads/bat_ads_client_notifier_impl.cc
index 8077d50af879..9945f3854867 100644
--- a/components/services/bat_ads/bat_ads_client_notifier_impl.cc
+++ b/components/services/bat_ads/bat_ads_client_notifier_impl.cc
@@ -13,7 +13,10 @@ BatAdsClientNotifierImpl::BatAdsClientNotifierImpl(
     mojo::PendingReceiver<mojom::BatAdsClientNotifier>
         bat_ads_client_notifier_pending_receiver)
     : bat_ads_client_notifier_pending_receiver_(
-          std::move(bat_ads_client_notifier_pending_receiver)) {}
+          std::move(bat_ads_client_notifier_pending_receiver)) {
+  bat_ads_client_notifier_receiver_.Bind(
+      std::move(bat_ads_client_notifier_pending_receiver_));
+}
 
 BatAdsClientNotifierImpl::~BatAdsClientNotifierImpl() = default;
 
@@ -31,10 +34,8 @@ void BatAdsClientNotifierImpl::RemoveObserver(
   ads_client_notifier_.RemoveObserver(observer);
 }
 
-void BatAdsClientNotifierImpl::BindReceiver() {
-  CHECK(bat_ads_client_notifier_pending_receiver_.is_valid());
-  bat_ads_client_notifier_receiver_.Bind(
-      std::move(bat_ads_client_notifier_pending_receiver_));
+void BatAdsClientNotifierImpl::NotifyPendingObservers() {
+  ads_client_notifier_.NotifyPendingObservers();
 }
 
 void BatAdsClientNotifierImpl::NotifyDidInitializeAds() {
diff --git a/components/services/bat_ads/bat_ads_client_notifier_impl.h b/components/services/bat_ads/bat_ads_client_notifier_impl.h
index 0aff62cfd5a3..17c6e12970e8 100644
--- a/components/services/bat_ads/bat_ads_client_notifier_impl.h
+++ b/components/services/bat_ads/bat_ads_client_notifier_impl.h
@@ -37,8 +37,8 @@ class BatAdsClientNotifierImpl : public bat_ads::mojom::BatAdsClientNotifier {
   void AddObserver(brave_ads::AdsClientNotifierObserver* observer);
   void RemoveObserver(brave_ads::AdsClientNotifierObserver* observer);
 
-  // Binds the receiver by consuming the pending receiver swhich was created.
-  void BindReceiver();
+  // Invoked to fire all pending observer events.
+  void NotifyPendingObservers();
 
   // Invoked when ads did initialize.
   void NotifyDidInitializeAds() override;
diff --git a/components/services/bat_ads/bat_ads_impl.cc b/components/services/bat_ads/bat_ads_impl.cc
index 0947b34e3bae..f831c1915b19 100644
--- a/components/services/bat_ads/bat_ads_impl.cc
+++ b/components/services/bat_ads/bat_ads_impl.cc
@@ -96,15 +96,21 @@ void BatAdsImpl::Shutdown(ShutdownCallback callback) {
 void BatAdsImpl::MaybeGetNotificationAd(
     const std::string& placement_id,
     MaybeGetNotificationAdCallback callback) {
-  const std::optional<brave_ads::NotificationAdInfo> ad =
-      GetAds()->MaybeGetNotificationAd(placement_id);
-  if (!ad) {
-    std::move(callback).Run(/*ad*/ std::nullopt);
-    return;
-  }
+  GetAds()->MaybeGetNotificationAd(
+      placement_id,
+      base::BindOnce(
+          [](MaybeGetNotificationAdCallback callback,
+             const std::optional<brave_ads::NotificationAdInfo>& ad) {
+            if (!ad) {
+              std::move(callback).Run(/*ad*/ std::nullopt);
+              return;
+            }
 
-  std::optional<base::Value::Dict> dict = brave_ads::NotificationAdToValue(*ad);
-  std::move(callback).Run(std::move(dict));
+            std::optional<base::Value::Dict> dict =
+                brave_ads::NotificationAdToValue(*ad);
+            std::move(callback).Run(std::move(dict));
+          },
+          std::move(callback)));
 }
 
 void BatAdsImpl::TriggerNotificationAdEvent(
diff --git a/ios/browser/api/ads/brave_ads.h b/ios/browser/api/ads/brave_ads.h
index 174ea1a75fe9..6077d9cfd771 100644
--- a/ios/browser/api/ads/brave_ads.h
+++ b/ios/browser/api/ads/brave_ads.h
@@ -113,7 +113,8 @@ OBJC_EXPORT
                        eventType:(BraveAdsNewTabPageAdEventType)eventType
                       completion:(void (^)(BOOL success))completion;
 
-- (nullable NotificationAdIOS*)maybeGetNotificationAd:(NSString*)identifier;
+- (void)maybeGetNotificationAd:(NSString*)identifier
+                    completion:(void (^)(NotificationAdIOS*))completion;
 
 - (void)triggerNotificationAdEvent:(NSString*)placementId
                          eventType:(BraveAdsNotificationAdEventType)eventType
diff --git a/ios/browser/api/ads/brave_ads.mm b/ios/browser/api/ads/brave_ads.mm
index 4f9780fd8169..a9c86fefba2e 100644
--- a/ios/browser/api/ads/brave_ads.mm
+++ b/ios/browser/api/ads/brave_ads.mm
@@ -1587,18 +1587,25 @@ - (void)triggerNewTabPageAdEvent:(NSString*)wallpaperId
       base::BindOnce(completion));
 }
 
-- (nullable NotificationAdIOS*)maybeGetNotificationAd:(NSString*)identifier {
+- (void)maybeGetNotificationAd:(NSString*)identifier
+                    completion:(void (^)(NotificationAdIOS*))completion {
   if (![self isServiceRunning]) {
-    return nil;
+    completion(nil);
+    return;
   }
 
-  const std::optional<brave_ads::NotificationAdInfo> ad =
-      ads->MaybeGetNotificationAd(identifier.UTF8String);
-  if (!ad) {
-    return nil;
-  }
+  ads->MaybeGetNotificationAd(
+      identifier.UTF8String,
+      base::BindOnce(^(const std::optional<brave_ads::NotificationAdInfo>& ad) {
+        if (!ad) {
+          completion(nil);
+          return;
+        }
 
-  return [[NotificationAdIOS alloc] initWithNotificationAdInfo:*ad];
+        const auto notification_ad =
+            [[NotificationAdIOS alloc] initWithNotificationAdInfo:*ad];
+        completion(notification_ad);
+      }));
 }
 
 - (void)triggerNotificationAdEvent:(NSString*)placementId