diff --git a/browser/ephemeral_storage/ephemeral_storage_browsertest.cc b/browser/ephemeral_storage/ephemeral_storage_browsertest.cc
index c40bd38b4a53..867fbd4d97c0 100644
--- a/browser/ephemeral_storage/ephemeral_storage_browsertest.cc
+++ b/browser/ephemeral_storage/ephemeral_storage_browsertest.cc
@@ -59,15 +59,29 @@ content::EvalJsResult GetStorageValueInFrame(RenderFrameHost* host,
   return content::EvalJs(host, script);
 }
 
+content::EvalJsResult GetStorageInFrame(RenderFrameHost* host,
+                                        StorageType storage_type) {
+  std::string script = base::StringPrintf("%sStorage;", ToString(storage_type));
+  return content::EvalJs(host, script);
+}
+
+void AssertStorageEmptyInFrame(RenderFrameHost* frame) {
+  EXPECT_EQ(nullptr, GetStorageInFrame(frame, StorageType::Local));
+  EXPECT_EQ(nullptr, GetStorageInFrame(frame, StorageType::Session));
+}
+
+void AssertStorageEmptyInSubframes(WebContents* web_contents) {
+  RenderFrameHost* main_frame = web_contents->GetMainFrame();
+  AssertStorageEmptyInFrame(content::ChildFrameAt(main_frame, 0));
+  AssertStorageEmptyInFrame(content::ChildFrameAt(main_frame, 1));
+}
+
 }  // namespace
 
-class EphemeralStorageBrowserTest : public InProcessBrowserTest {
+class EphemeralStorageBaseBrowserTest : public InProcessBrowserTest {
  public:
-  EphemeralStorageBrowserTest()
-      : https_server_(net::EmbeddedTestServer::TYPE_HTTPS) {
-    scoped_feature_list_.InitAndEnableFeature(
-        blink::features::kBraveEphemeralStorage);
-  }
+  EphemeralStorageBaseBrowserTest()
+      : https_server_(net::EmbeddedTestServer::TYPE_HTTPS) {}
 
   void SetUpOnMainThread() override {
     InProcessBrowserTest::SetUpOnMainThread();
@@ -162,12 +176,18 @@ class EphemeralStorageBrowserTest : public InProcessBrowserTest {
   GURL c_site_ephemeral_storage_url_;
 
  private:
-  DISALLOW_COPY_AND_ASSIGN(EphemeralStorageBrowserTest);
+  DISALLOW_COPY_AND_ASSIGN(EphemeralStorageBaseBrowserTest);
 };
 
-IN_PROC_BROWSER_TEST_F(EphemeralStorageBrowserTest, StorageIsPartitioned) {
-  AllowAllCookies();
+class EphemeralStorageBrowserTest : public EphemeralStorageBaseBrowserTest {
+ public:
+  EphemeralStorageBrowserTest() {
+    scoped_feature_list_.InitAndEnableFeature(
+        blink::features::kBraveEphemeralStorage);
+  }
+};
 
+IN_PROC_BROWSER_TEST_F(EphemeralStorageBrowserTest, StorageIsPartitioned) {
   WebContents* first_party_tab = LoadURLInNewTab(b_site_ephemeral_storage_url_);
   WebContents* site_a_tab1 = LoadURLInNewTab(a_site_ephemeral_storage_url_);
   WebContents* site_a_tab2 = LoadURLInNewTab(a_site_ephemeral_storage_url_);
@@ -229,8 +249,6 @@ IN_PROC_BROWSER_TEST_F(EphemeralStorageBrowserTest, StorageIsPartitioned) {
 
 IN_PROC_BROWSER_TEST_F(EphemeralStorageBrowserTest,
                        NavigatingClearsEphemeralStorage) {
-  AllowAllCookies();
-
   ui_test_utils::NavigateToURL(browser(), a_site_ephemeral_storage_url_);
   auto* web_contents = browser()->tab_strip_model()->GetActiveWebContents();
 
@@ -261,8 +279,6 @@ IN_PROC_BROWSER_TEST_F(EphemeralStorageBrowserTest,
 
 IN_PROC_BROWSER_TEST_F(EphemeralStorageBrowserTest,
                        ClosingTabClearsEphemeralStorage) {
-  AllowAllCookies();
-
   WebContents* site_a_tab = LoadURLInNewTab(a_site_ephemeral_storage_url_);
   EXPECT_EQ(browser()->tab_strip_model()->count(), 2);
 
@@ -303,8 +319,6 @@ IN_PROC_BROWSER_TEST_F(EphemeralStorageBrowserTest,
 
 IN_PROC_BROWSER_TEST_F(EphemeralStorageBrowserTest,
                        ReloadDoesNotClearEphemeralStorage) {
-  AllowAllCookies();
-
   ui_test_utils::NavigateToURL(browser(), a_site_ephemeral_storage_url_);
   auto* web_contents = browser()->tab_strip_model()->GetActiveWebContents();
 
@@ -334,8 +348,6 @@ IN_PROC_BROWSER_TEST_F(EphemeralStorageBrowserTest,
 
 IN_PROC_BROWSER_TEST_F(EphemeralStorageBrowserTest,
                        EphemeralStorageDoesNotLeakBetweenProfiles) {
-  AllowAllCookies();
-
   ui_test_utils::NavigateToURL(browser(), a_site_ephemeral_storage_url_);
   auto* web_contents = browser()->tab_strip_model()->GetActiveWebContents();
 
@@ -384,3 +396,106 @@ IN_PROC_BROWSER_TEST_F(EphemeralStorageBrowserTest,
   EXPECT_EQ(nullptr, private_values.iframe_1.session_storage);
   EXPECT_EQ(nullptr, private_values.iframe_2.session_storage);
 }
+
+IN_PROC_BROWSER_TEST_F(EphemeralStorageBrowserTest, ThirdPartyCookiesEnabled) {
+  AllowAllCookies();
+
+  ui_test_utils::NavigateToURL(browser(), b_site_ephemeral_storage_url_);
+  auto* web_contents = browser()->tab_strip_model()->GetActiveWebContents();
+  // We set a value in the page where all the frames are first-party.
+  SetValuesInFrames(web_contents, "b.com - first party", "from=b.com");
+
+  // The storage in the first-party iframes should still reflect the
+  // original value that was written in the non-ephemeral storage area.
+  ValuesFromFrames first_party_values = GetValuesFromFrames(web_contents);
+  EXPECT_EQ("b.com - first party", first_party_values.main_frame.local_storage);
+  EXPECT_EQ("b.com - first party", first_party_values.iframe_1.local_storage);
+  EXPECT_EQ("b.com - first party", first_party_values.iframe_2.local_storage);
+
+  EXPECT_EQ("b.com - first party",
+            first_party_values.main_frame.session_storage);
+  EXPECT_EQ("b.com - first party", first_party_values.iframe_1.session_storage);
+  EXPECT_EQ("b.com - first party", first_party_values.iframe_2.session_storage);
+
+  ui_test_utils::NavigateToURL(browser(), a_site_ephemeral_storage_url_);
+  auto* a_site_content = browser()->tab_strip_model()->GetActiveWebContents();
+
+  // If third-party cookies is enabled, site_a_tab should be able to access to
+  // non-ephemeral sotrages.
+  ValuesFromFrames site_a_tab_values = GetValuesFromFrames(a_site_content);
+  EXPECT_EQ(nullptr, site_a_tab_values.main_frame.local_storage);
+  EXPECT_EQ("b.com - first party", site_a_tab_values.iframe_1.local_storage);
+  EXPECT_EQ("b.com - first party", site_a_tab_values.iframe_2.local_storage);
+
+  EXPECT_EQ(nullptr, site_a_tab_values.main_frame.session_storage);
+  EXPECT_EQ("b.com - first party", site_a_tab_values.iframe_1.session_storage);
+  EXPECT_EQ("b.com - first party", site_a_tab_values.iframe_2.session_storage);
+}
+
+class EphemeralStorageDisabledBrowserTest
+    : public EphemeralStorageBaseBrowserTest {
+ public:
+  EphemeralStorageDisabledBrowserTest() {
+    scoped_feature_list_.InitAndDisableFeature(
+        blink::features::kBraveEphemeralStorage);
+  }
+};
+
+IN_PROC_BROWSER_TEST_F(EphemeralStorageDisabledBrowserTest,
+                       ThirdPartyCookiesEnabled) {
+  AllowAllCookies();
+
+  ui_test_utils::NavigateToURL(browser(), b_site_ephemeral_storage_url_);
+  auto* web_contents = browser()->tab_strip_model()->GetActiveWebContents();
+  // We set a value in the page where all the frames are first-party.
+  SetValuesInFrames(web_contents, "b.com - first party", "from=b.com");
+
+  ValuesFromFrames first_party_values = GetValuesFromFrames(web_contents);
+  EXPECT_EQ("b.com - first party", first_party_values.main_frame.local_storage);
+  EXPECT_EQ("b.com - first party", first_party_values.iframe_1.local_storage);
+  EXPECT_EQ("b.com - first party", first_party_values.iframe_2.local_storage);
+
+  EXPECT_EQ("b.com - first party",
+            first_party_values.main_frame.session_storage);
+  EXPECT_EQ("b.com - first party", first_party_values.iframe_1.session_storage);
+  EXPECT_EQ("b.com - first party", first_party_values.iframe_2.session_storage);
+
+  ui_test_utils::NavigateToURL(browser(), a_site_ephemeral_storage_url_);
+  auto* a_site_content = browser()->tab_strip_model()->GetActiveWebContents();
+
+  // If third-party cookies is enabled, site_a_tab should be able to access to
+  // non-ephemeral sotrages.
+  ValuesFromFrames site_a_tab_values = GetValuesFromFrames(a_site_content);
+  EXPECT_EQ(nullptr, site_a_tab_values.main_frame.local_storage);
+  EXPECT_EQ("b.com - first party", site_a_tab_values.iframe_1.local_storage);
+  EXPECT_EQ("b.com - first party", site_a_tab_values.iframe_2.local_storage);
+
+  EXPECT_EQ(nullptr, site_a_tab_values.main_frame.session_storage);
+  EXPECT_EQ("b.com - first party", site_a_tab_values.iframe_1.session_storage);
+  EXPECT_EQ("b.com - first party", site_a_tab_values.iframe_2.session_storage);
+}
+
+IN_PROC_BROWSER_TEST_F(EphemeralStorageDisabledBrowserTest,
+                       ThirdPartyCookiesDisabled) {
+  ui_test_utils::NavigateToURL(browser(), b_site_ephemeral_storage_url_);
+  auto* web_contents = browser()->tab_strip_model()->GetActiveWebContents();
+  // We set a value in the page where all the frames are first-party.
+  SetValuesInFrames(web_contents, "b.com - first party", "from=b.com");
+
+  ValuesFromFrames first_party_values = GetValuesFromFrames(web_contents);
+  EXPECT_EQ("b.com - first party", first_party_values.main_frame.local_storage);
+  EXPECT_EQ("b.com - first party", first_party_values.iframe_1.local_storage);
+  EXPECT_EQ("b.com - first party", first_party_values.iframe_2.local_storage);
+
+  EXPECT_EQ("b.com - first party",
+            first_party_values.main_frame.session_storage);
+  EXPECT_EQ("b.com - first party", first_party_values.iframe_1.session_storage);
+  EXPECT_EQ("b.com - first party", first_party_values.iframe_2.session_storage);
+
+  ui_test_utils::NavigateToURL(browser(), a_site_ephemeral_storage_url_);
+  auto* a_site_content = browser()->tab_strip_model()->GetActiveWebContents();
+
+  // If both ephemeral storage and third-party cookies disabled, third-party
+  // frames can not access to any dom storage.
+  AssertStorageEmptyInSubframes(a_site_content);
+}
diff --git a/chromium_src/third_party/blink/renderer/modules/storage/dom_window_storage.cc b/chromium_src/third_party/blink/renderer/modules/storage/dom_window_storage.cc
index a45aed40b3aa..94be7731c126 100644
--- a/chromium_src/third_party/blink/renderer/modules/storage/dom_window_storage.cc
+++ b/chromium_src/third_party/blink/renderer/modules/storage/dom_window_storage.cc
@@ -170,17 +170,15 @@ StorageArea* BraveDOMWindowStorage::sessionStorage(
       DOMWindowStorage::From(*window).sessionStorage(exception_state);
 
   MaybeClearAccessDeniedException(storage, *window, &exception_state);
-  if (!base::FeatureList::IsEnabled(features::kBraveEphemeralStorage))
-    return storage;
-
-  if (!window->IsCrossSiteSubframe())
-    return storage;
-
   // If we were not able to create non-ephemeral session storage for this
   // window, then don't attempt to create an ephemeral version.
   if (!storage)
     return nullptr;
 
+  if (StorageController::CanAccessStorageAreaWithoutEphemeral(
+          window->GetFrame(), StorageArea::StorageType::kSessionStorage))
+    return storage;
+
   return ephemeralSessionStorage();
 }
 
@@ -210,17 +208,15 @@ StorageArea* BraveDOMWindowStorage::localStorage(
   auto* storage = DOMWindowStorage::From(*window).localStorage(exception_state);
 
   MaybeClearAccessDeniedException(storage, *window, &exception_state);
-  if (!base::FeatureList::IsEnabled(features::kBraveEphemeralStorage))
-    return storage;
-
-  if (!window->IsCrossSiteSubframe())
-    return storage;
-
   // If we were not able to create non-ephemeral localStorage for this Window,
   // then don't attempt to create an ephemeral version.
   if (!storage)
     return nullptr;
 
+  if (StorageController::CanAccessStorageAreaWithoutEphemeral(
+          window->GetFrame(), StorageArea::StorageType::kSessionStorage))
+    return storage;
+
   return ephemeralLocalStorage();
 }
 
diff --git a/chromium_src/third_party/blink/renderer/modules/storage/storage_controller.cc b/chromium_src/third_party/blink/renderer/modules/storage/storage_controller.cc
new file mode 100644
index 000000000000..1e802be915e1
--- /dev/null
+++ b/chromium_src/third_party/blink/renderer/modules/storage/storage_controller.cc
@@ -0,0 +1,29 @@
+/* Copyright (c) 2020 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 http://mozilla.org/MPL/2.0/. */
+
+#include "third_party/blink/renderer/modules/storage/storage_controller.h"
+
+#include "third_party/blink/public/common/features.h"
+#include "third_party/blink/renderer/core/frame/local_dom_window.h"
+#include "third_party/blink/renderer/core/frame/local_frame.h"
+
+namespace blink {
+
+// static
+bool StorageController::CanAccessStorageArea(LocalFrame* frame,
+                                             StorageArea::StorageType type) {
+  if (CanAccessStorageAreaWithoutEphemeral(frame, type))
+    return true;
+  if (frame && frame->GetDocument() && frame->GetDocument()->domWindow() &&
+      frame->GetDocument()->domWindow()->IsCrossSiteSubframe())
+    return base::FeatureList::IsEnabled(features::kBraveEphemeralStorage);
+  return false;
+}
+
+}  // namespace blink
+
+#define CanAccessStorageArea CanAccessStorageAreaWithoutEphemeral
+#include "../../../../../../../third_party/blink/renderer/modules/storage/storage_controller.cc"
+#undef CanAccessStorageAreaWithoutEphemeral
diff --git a/chromium_src/third_party/blink/renderer/modules/storage/storage_controller.h b/chromium_src/third_party/blink/renderer/modules/storage/storage_controller.h
new file mode 100644
index 000000000000..4a8e1f498287
--- /dev/null
+++ b/chromium_src/third_party/blink/renderer/modules/storage/storage_controller.h
@@ -0,0 +1,18 @@
+/* Copyright (c) 2020 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 http://mozilla.org/MPL/2.0/. */
+
+#ifndef BRAVE_CHROMIUM_SRC_THIRD_PARTY_BLINK_RENDERER_MODULES_STORAGE_STORAGE_CONTROLLER_H_
+#define BRAVE_CHROMIUM_SRC_THIRD_PARTY_BLINK_RENDERER_MODULES_STORAGE_STORAGE_CONTROLLER_H_
+
+#define BRAVE_STORAGE_CONTROLLER_H                  \
+ public:                                            \
+  static bool CanAccessStorageAreaWithoutEphemeral( \
+      LocalFrame* frame, StorageArea::StorageType type);
+
+#include "../../../../../../../third_party/blink/renderer/modules/storage/storage_controller.h"
+
+#undef BRAVE_STORAGE_CONTROLLER_H
+
+#endif  // BRAVE_CHROMIUM_SRC_THIRD_PARTY_BLINK_RENDERER_MODULES_STORAGE_STORAGE_CONTROLLER_H_
diff --git a/patches/third_party-blink-renderer-modules-storage-storage_controller.h.patch b/patches/third_party-blink-renderer-modules-storage-storage_controller.h.patch
new file mode 100644
index 000000000000..ac56cc46f47c
--- /dev/null
+++ b/patches/third_party-blink-renderer-modules-storage-storage_controller.h.patch
@@ -0,0 +1,12 @@
+diff --git a/third_party/blink/renderer/modules/storage/storage_controller.h b/third_party/blink/renderer/modules/storage/storage_controller.h
+index 554f6cbaadec5b247452b68ffe332d1210cd4a81..6d8e3adec71bbbf7782671f4d0138f30ecebac39 100644
+--- a/third_party/blink/renderer/modules/storage/storage_controller.h
++++ b/third_party/blink/renderer/modules/storage/storage_controller.h
+@@ -96,6 +96,7 @@ class MODULES_EXPORT StorageController : public mojom::blink::DomStorageClient {
+     return task_runner_;
+   }
+ 
++  BRAVE_STORAGE_CONTROLLER_H
+  private:
+   void EnsureLocalStorageNamespaceCreated();
+