diff --git a/mobile/android/android-components/components/browser/engine-gecko/src/main/java/mozilla/components/browser/engine/gecko/GeckoEngine.kt b/mobile/android/android-components/components/browser/engine-gecko/src/main/java/mozilla/components/browser/engine/gecko/GeckoEngine.kt
index a6abfcb09a8..4168b63f02a 100644
--- a/mobile/android/android-components/components/browser/engine-gecko/src/main/java/mozilla/components/browser/engine/gecko/GeckoEngine.kt
+++ b/mobile/android/android-components/components/browser/engine-gecko/src/main/java/mozilla/components/browser/engine/gecko/GeckoEngine.kt
@@ -152,8 +152,17 @@ class GeckoEngine(
         }
     }
     private val webExtensionTabHandler = object : TabHandler {
-        override fun onNewTab(webExtension: WebExtension, engineSession: EngineSession, active: Boolean, url: String) {
-            webExtensionDelegate?.onNewTab(webExtension, engineSession, active, url)
+        override fun isInPrivateBrowsing(): Boolean =
+            webExtensionDelegate?.isInPrivateBrowsing() ?: false
+
+        override fun onNewTab(
+            webExtension: WebExtension,
+            engineSession: EngineSession,
+            active: Boolean,
+            url: String,
+            isPrivate: Boolean,
+        ) {
+            webExtensionDelegate?.onNewTab(webExtension, engineSession, active, url, isPrivate)
         }
 
         override fun onOpenOptionsPage(extension: WebExtension) {
diff --git a/mobile/android/android-components/components/browser/engine-gecko/src/main/java/mozilla/components/browser/engine/gecko/webextension/GeckoWebExtension.kt b/mobile/android/android-components/components/browser/engine-gecko/src/main/java/mozilla/components/browser/engine/gecko/webextension/GeckoWebExtension.kt
index 8633cb91821..e611d576910 100644
--- a/mobile/android/android-components/components/browser/engine-gecko/src/main/java/mozilla/components/browser/engine/gecko/webextension/GeckoWebExtension.kt
+++ b/mobile/android/android-components/components/browser/engine-gecko/src/main/java/mozilla/components/browser/engine/gecko/webextension/GeckoWebExtension.kt
@@ -260,8 +260,11 @@ class GeckoWebExtension(
                 ext: GeckoNativeWebExtension,
                 tabDetails: GeckoNativeWebExtension.CreateTabDetails,
             ): GeckoResult<GeckoSession>? {
+                // TODO bug 1372178: extensions cannot set (non-)privateness.
+                val isPrivate = tabHandler.isInPrivateBrowsing()
                 val geckoEngineSession = GeckoEngineSession(
                     runtime = runtime,
+                    privateMode = isPrivate,
                     defaultSettings = defaultSettings,
                     openGeckoSession = false,
                 )
@@ -271,6 +274,7 @@ class GeckoWebExtension(
                     geckoEngineSession,
                     tabDetails.active == true,
                     tabDetails.url ?: "",
+                    isPrivate,
                 )
                 return GeckoResult.fromValue(geckoEngineSession.geckoSession)
             }
diff --git a/mobile/android/android-components/components/browser/engine-gecko/src/test/java/mozilla/components/browser/engine/gecko/GeckoEngineTest.kt b/mobile/android/android-components/components/browser/engine-gecko/src/test/java/mozilla/components/browser/engine/gecko/GeckoEngineTest.kt
index 376a205c8d1..19f680f72b8 100644
--- a/mobile/android/android-components/components/browser/engine-gecko/src/test/java/mozilla/components/browser/engine/gecko/GeckoEngineTest.kt
+++ b/mobile/android/android-components/components/browser/engine-gecko/src/test/java/mozilla/components/browser/engine/gecko/GeckoEngineTest.kt
@@ -1972,7 +1972,7 @@ class GeckoEngineTest {
         tabDelegateCaptor.value.onNewTab(extension, createTabDetails)
 
         val extensionCaptor = argumentCaptor<WebExtension>()
-        verify(webExtensionsDelegate).onNewTab(extensionCaptor.capture(), any(), eq(false), eq(""))
+        verify(webExtensionsDelegate).onNewTab(extensionCaptor.capture(), any(), eq(false), eq(""), eq(false))
         assertEquals(extId, extensionCaptor.value.id)
     }
 
@@ -2076,7 +2076,7 @@ class GeckoEngineTest {
         tabDelegateCaptor.value.onNewTab(extension, createTabDetails)
 
         val extensionCaptor = argumentCaptor<WebExtension>()
-        verify(webExtensionsDelegate).onNewTab(extensionCaptor.capture(), any(), eq(false), eq(""))
+        verify(webExtensionsDelegate).onNewTab(extensionCaptor.capture(), any(), eq(false), eq(""), eq(false))
         assertEquals(extId, extensionCaptor.value.id)
     }
 
diff --git a/mobile/android/android-components/components/browser/engine-gecko/src/test/java/mozilla/components/browser/engine/gecko/webextension/GeckoWebExtensionTest.kt b/mobile/android/android-components/components/browser/engine-gecko/src/test/java/mozilla/components/browser/engine/gecko/webextension/GeckoWebExtensionTest.kt
index 0115b874a8d..cd4f8f3731e 100644
--- a/mobile/android/android-components/components/browser/engine-gecko/src/test/java/mozilla/components/browser/engine/gecko/webextension/GeckoWebExtensionTest.kt
+++ b/mobile/android/android-components/components/browser/engine-gecko/src/test/java/mozilla/components/browser/engine/gecko/webextension/GeckoWebExtensionTest.kt
@@ -340,13 +340,54 @@ class GeckoWebExtensionTest {
         // Verify that tab methods are forwarded to the handler
         val tabDetails = mockCreateTabDetails(active = true, url = "url")
         tabDelegateCaptor.value.onNewTab(nativeGeckoWebExt, tabDetails)
-        verify(tabHandler).onNewTab(eq(extension), engineSessionCaptor.capture(), eq(true), eq("url"))
+        verify(tabHandler).onNewTab(eq(extension), engineSessionCaptor.capture(), eq(true), eq("url"), eq(false))
         assertNotNull(engineSessionCaptor.value)
+        assertFalse(engineSessionCaptor.value.geckoSession.settings.usePrivateMode)
 
         tabDelegateCaptor.value.onOpenOptionsPage(nativeGeckoWebExt)
         verify(tabHandler).onOpenOptionsPage(eq(extension))
     }
 
+    @Test
+    fun `global tab handler opens a private tab when private browsing mode is active`() {
+        val runtime: GeckoRuntime = mock()
+        whenever(runtime.settings).thenReturn(mock())
+        whenever(runtime.webExtensionController).thenReturn(mock())
+        val tabHandler: TabHandler = mock()
+        val tabDelegateCaptor = argumentCaptor<WebExtension.TabDelegate>()
+        val engineSessionCaptor = argumentCaptor<GeckoEngineSession>()
+
+        val nativeGeckoWebExt: WebExtension =
+            mockNativeWebExtension(id = "id", location = "uri", metaData = mockNativeWebExtensionMetaData())
+
+        // Create extension and register global tab handler
+        val extension = GeckoWebExtension(
+            runtime = runtime,
+            nativeExtension = nativeGeckoWebExt,
+        )
+        val defaultSettings: DefaultSettings = mock()
+
+        // Simulate that the user has enabled private browsing.
+        whenever(tabHandler.isInPrivateBrowsing()).thenReturn(true)
+
+        extension.registerTabHandler(tabHandler, defaultSettings)
+        verify(nativeGeckoWebExt).tabDelegate = tabDelegateCaptor.capture()
+
+        // Simulate browser.tabs.create() call from extension.
+        val tabDetails = mockCreateTabDetails(active = true, url = "url")
+        tabDelegateCaptor.value.onNewTab(nativeGeckoWebExt, tabDetails)
+        verify(tabHandler).onNewTab(eq(extension), engineSessionCaptor.capture(), eq(true), eq("url"), eq(true))
+        assertTrue(engineSessionCaptor.value.geckoSession.settings.usePrivateMode)
+
+        // Simulate that the user switched back to non-private browsing.
+        whenever(tabHandler.isInPrivateBrowsing()).thenReturn(false)
+
+        // Now browser.tabs.create() should open in a non-private browsing context.
+        tabDelegateCaptor.value.onNewTab(nativeGeckoWebExt, tabDetails)
+        verify(tabHandler).onNewTab(eq(extension), engineSessionCaptor.capture(), eq(true), eq("url"), eq(false))
+        assertFalse(engineSessionCaptor.value.geckoSession.settings.usePrivateMode)
+    }
+
     @Test
     fun `register session-specific tab handler`() {
         val runtime: GeckoRuntime = mock()
diff --git a/mobile/android/android-components/components/concept/engine/src/main/java/mozilla/components/concept/engine/webextension/WebExtension.kt b/mobile/android/android-components/components/concept/engine/src/main/java/mozilla/components/concept/engine/webextension/WebExtension.kt
index 1c22cc1e5bb..ee98a9dbe1c 100644
--- a/mobile/android/android-components/components/concept/engine/src/main/java/mozilla/components/concept/engine/webextension/WebExtension.kt
+++ b/mobile/android/android-components/components/concept/engine/src/main/java/mozilla/components/concept/engine/webextension/WebExtension.kt
@@ -302,6 +302,11 @@ interface MessageHandler {
  * A handler for all tab related events (triggered by browser.tabs.* methods).
  */
 interface TabHandler {
+    /**
+     * Invoked to determine the current private browsing mode. New tabs opened
+     * by extensions may use this state if not specified otherwise.
+     */
+    fun isInPrivateBrowsing(): Boolean = false
 
     /**
      * Invoked when a web extension attempts to open a new tab via
@@ -311,8 +316,16 @@ interface TabHandler {
      * @param engineSession an instance of engine session to open a new tab with.
      * @param active whether or not the new tab should be active/selected.
      * @param url the target url to be loaded in a new tab.
-     */
-    fun onNewTab(webExtension: WebExtension, engineSession: EngineSession, active: Boolean, url: String) = Unit
+     * @param isPrivate whether private browsing mode is enabled for the new
+     * tab. Must match the engineSession.privateMode flag.
+     */
+    fun onNewTab(
+        webExtension: WebExtension,
+        engineSession: EngineSession,
+        active: Boolean,
+        url: String,
+        isPrivate: Boolean,
+    ) = Unit
 
     /**
      * Invoked when a web extension attempts to update a tab via
diff --git a/mobile/android/android-components/components/concept/engine/src/main/java/mozilla/components/concept/engine/webextension/WebExtensionDelegate.kt b/mobile/android/android-components/components/concept/engine/src/main/java/mozilla/components/concept/engine/webextension/WebExtensionDelegate.kt
index 86eeb61a442..11827ac028e 100644
--- a/mobile/android/android-components/components/concept/engine/src/main/java/mozilla/components/concept/engine/webextension/WebExtensionDelegate.kt
+++ b/mobile/android/android-components/components/concept/engine/src/main/java/mozilla/components/concept/engine/webextension/WebExtensionDelegate.kt
@@ -62,6 +62,12 @@ interface WebExtensionDelegate {
      */
     fun onAllowedInPrivateBrowsingChanged(extension: WebExtension) = Unit
 
+    /**
+     * Invoked to determine the current private browsing mode. New tabs opened
+     * by extensions may use this state if not specified otherwise.
+     */
+    fun isInPrivateBrowsing(): Boolean = false
+
     /**
      * Invoked when a web extension attempts to open a new tab via
      * browser.tabs.create. Note that browser.tabs.update and browser.tabs.remove
@@ -72,8 +78,16 @@ interface WebExtensionDelegate {
      * @param engineSession an instance of engine session to open a new tab with.
      * @param active whether or not the new tab should be active/selected.
      * @param url the target url to be loaded in a new tab.
+     * @param isPrivate whether private browsing mode is enabled for the new
+     * tab. Must match the engineSession.privateMode flag.
      */
-    fun onNewTab(extension: WebExtension, engineSession: EngineSession, active: Boolean, url: String) = Unit
+    fun onNewTab(
+        extension: WebExtension,
+        engineSession: EngineSession,
+        active: Boolean,
+        url: String,
+        isPrivate: Boolean,
+    ) = Unit
 
     /**
      * Invoked when a web extension defines a browser action. To listen for session-specific

diff --git a/mobile/android/android-components/components/browser/engine-gecko/src/test/java/mozilla/components/browser/engine/gecko/GeckoEngineTest.kt b/mobile/android/android-components/components/browser/engine-gecko/src/test/java/mozilla/components/browser/engine/gecko/GeckoEngineTest.kt
index 376a205c8d1..19f680f72b8 100644
--- a/mobile/android/android-components/components/browser/engine-gecko/src/test/java/mozilla/components/browser/engine/gecko/GeckoEngineTest.kt
+++ b/mobile/android/android-components/components/browser/engine-gecko/src/test/java/mozilla/components/browser/engine/gecko/GeckoEngineTest.kt
@@ -1972,7 +1972,7 @@ class GeckoEngineTest {
         tabDelegateCaptor.value.onNewTab(extension, createTabDetails)
 
         val extensionCaptor = argumentCaptor<WebExtension>()
-        verify(webExtensionsDelegate).onNewTab(extensionCaptor.capture(), any(), eq(false), eq(""))
+        verify(webExtensionsDelegate).onNewTab(extensionCaptor.capture(), any(), eq(false), eq(""), eq(false))
         assertEquals(extId, extensionCaptor.value.id)
     }
 
@@ -2076,7 +2076,7 @@ class GeckoEngineTest {
         tabDelegateCaptor.value.onNewTab(extension, createTabDetails)
 
         val extensionCaptor = argumentCaptor<WebExtension>()
-        verify(webExtensionsDelegate).onNewTab(extensionCaptor.capture(), any(), eq(false), eq(""))
+        verify(webExtensionsDelegate).onNewTab(extensionCaptor.capture(), any(), eq(false), eq(""), eq(false))
         assertEquals(extId, extensionCaptor.value.id)
     }
diff --git a/mobile/android/android-components/components/browser/engine-gecko/src/test/java/mozilla/components/browser/engine/gecko/webextension/GeckoWebExtensionTest.kt b/mobile/android/android-components/components/browser/engine-gecko/src/test/java/mozilla/components/browser/engine/gecko/webextension/GeckoWebExtensionTest.kt
index 0115b874a8d..cd4f8f3731e 100644
--- a/mobile/android/android-components/components/browser/engine-gecko/src/test/java/mozilla/components/browser/engine/gecko/webextension/GeckoWebExtensionTest.kt
+++ b/mobile/android/android-components/components/browser/engine-gecko/src/test/java/mozilla/components/browser/engine/gecko/webextension/GeckoWebExtensionTest.kt
@@ -340,13 +340,54 @@ class GeckoWebExtensionTest {
         // Verify that tab methods are forwarded to the handler
         val tabDetails = mockCreateTabDetails(active = true, url = "url")
         tabDelegateCaptor.value.onNewTab(nativeGeckoWebExt, tabDetails)
-        verify(tabHandler).onNewTab(eq(extension), engineSessionCaptor.capture(), eq(true), eq("url"))
+        verify(tabHandler).onNewTab(eq(extension), engineSessionCaptor.capture(), eq(true), eq("url"), eq(false))
         assertNotNull(engineSessionCaptor.value)
+        assertFalse(engineSessionCaptor.value.geckoSession.settings.usePrivateMode)
 
         tabDelegateCaptor.value.onOpenOptionsPage(nativeGeckoWebExt)
         verify(tabHandler).onOpenOptionsPage(eq(extension))
     }
 
+    @Test
+    fun `global tab handler opens a private tab when private browsing mode is active`() {
+        val runtime: GeckoRuntime = mock()
+        whenever(runtime.settings).thenReturn(mock())
+        whenever(runtime.webExtensionController).thenReturn(mock())
+        val tabHandler: TabHandler = mock()
+        val tabDelegateCaptor = argumentCaptor<WebExtension.TabDelegate>()
+        val engineSessionCaptor = argumentCaptor<GeckoEngineSession>()
+
+        val nativeGeckoWebExt: WebExtension =
+            mockNativeWebExtension(id = "id", location = "uri", metaData = mockNativeWebExtensionMetaData())
+
+        // Create extension and register global tab handler
+        val extension = GeckoWebExtension(
+            runtime = runtime,
+            nativeExtension = nativeGeckoWebExt,
+        )
+        val defaultSettings: DefaultSettings = mock()
+
+        // Simulate that the user has enabled private browsing.
+        whenever(tabHandler.isInPrivateBrowsing()).thenReturn(true)
+
+        extension.registerTabHandler(tabHandler, defaultSettings)
+        verify(nativeGeckoWebExt).tabDelegate = tabDelegateCaptor.capture()
+
+        // Simulate browser.tabs.create() call from extension.
+        val tabDetails = mockCreateTabDetails(active = true, url = "url")
+        tabDelegateCaptor.value.onNewTab(nativeGeckoWebExt, tabDetails)
+        verify(tabHandler).onNewTab(eq(extension), engineSessionCaptor.capture(), eq(true), eq("url"), eq(true))
+        assertTrue(engineSessionCaptor.value.geckoSession.settings.usePrivateMode)
+
+        // Simulate that the user switched back to non-private browsing.
+        whenever(tabHandler.isInPrivateBrowsing()).thenReturn(false)
+
+        // Now browser.tabs.create() should open in a non-private browsing context.
+        tabDelegateCaptor.value.onNewTab(nativeGeckoWebExt, tabDetails)
+        verify(tabHandler).onNewTab(eq(extension), engineSessionCaptor.capture(), eq(true), eq("url"), eq(false))
+        assertFalse(engineSessionCaptor.value.geckoSession.settings.usePrivateMode)
+    }
+
     @Test
     fun `register session-specific tab handler`() {
         val runtime: GeckoRuntime = mock()
diff --git a/mobile/android/android-components/components/concept/engine/src/test/java/mozilla/components/concept/engine/webextension/WebExtensionTest.kt b/mobile/android/android-components/components/concept/engine/src/test/java/mozilla/components/concept/engine/webextension/WebExtensionTest.kt
index 39e9e766ebc..50ebd89e4b1 100644
--- a/mobile/android/android-components/components/concept/engine/src/test/java/mozilla/components/concept/engine/webextension/WebExtensionTest.kt
+++ b/mobile/android/android-components/components/concept/engine/src/test/java/mozilla/components/concept/engine/webextension/WebExtensionTest.kt
@@ -31,7 +31,7 @@ class WebExtensionTest {
 
         tabHandler.onUpdateTab(mock(), mock(), false, "")
         tabHandler.onCloseTab(mock(), mock())
-        tabHandler.onNewTab(mock(), mock(), false, "")
+        tabHandler.onNewTab(mock(), mock(), false, "", false)
     }
 
     @Test
diff --git a/mobile/android/android-components/components/support/webextensions/src/test/java/mozilla/components/support/webextensions/WebExtensionSupportTest.kt b/mobile/android/android-components/components/support/webextensions/src/test/java/mozilla/components/support/webextensions/WebExtensionSupportTest.kt
index e31dd34ee26..8fc701e7efe 100644
--- a/mobile/android/android-components/components/support/webextensions/src/test/java/mozilla/components/support/webextensions/WebExtensionSupportTest.kt
+++ b/mobile/android/android-components/components/support/webextensions/src/test/java/mozilla/components/support/webextensions/WebExtensionSupportTest.kt
@@ -146,7 +146,7 @@ class WebExtensionSupportTest {
         WebExtensionSupport.initialize(engine, store)
         verify(engine).registerWebExtensionDelegate(delegateCaptor.capture())
 
-        delegateCaptor.value.onNewTab(ext, engineSession, true, "https://mozilla.org")
+        delegateCaptor.value.onNewTab(ext, engineSession, true, "https://mozilla.org", false)
 
         captureMiddleware.assertFirstAction(TabListAction.AddTabAction::class) { action ->
             assertEquals("https://mozilla.org", action.tab.content.url)
@@ -169,14 +169,14 @@ class WebExtensionSupportTest {
         WebExtensionSupport.initialize(
             engine,
             store,
-            onNewTabOverride = { _, _, _, _ ->
+            onNewTabOverride = { _, _, _, _, _ ->
                 onNewTabCalled = true
                 "123"
             },
         )
         verify(engine).registerWebExtensionDelegate(delegateCaptor.capture())
 
-        delegateCaptor.value.onNewTab(ext, engineSession, true, "https://mozilla.org")
+        delegateCaptor.value.onNewTab(ext, engineSession, true, "https://mozilla.org", false)
         assertTrue(onNewTabCalled)
     }
 
@@ -193,7 +193,7 @@ class WebExtensionSupportTest {
         WebExtensionSupport.initialize(
             engine,
             store,
-            onNewTabOverride = { _, _, _, selected ->
+            onNewTabOverride = { _, _, _, selected, _ ->
                 capturedSelected.add(selected)
                 "session-${capturedSelected.size}"
             },
@@ -203,8 +203,8 @@ class WebExtensionSupportTest {
         )
         verify(engine).registerWebExtensionDelegate(delegateCaptor.capture())
 
-        delegateCaptor.value.onNewTab(ext, engineSession, true, "https://mozilla.org")
-        delegateCaptor.value.onNewTab(ext, engineSession, false, "https://mozilla.org")
+        delegateCaptor.value.onNewTab(ext, engineSession, true, "https://mozilla.org", false)
+        delegateCaptor.value.onNewTab(ext, engineSession, false, "https://mozilla.org", false)
 
         assertEquals(listOf(true, false), capturedSelected)
         // onSelectTabOverride should only fire for the active=true case; the override
@@ -223,7 +223,7 @@ class WebExtensionSupportTest {
         WebExtensionSupport.initialize(engine, store)
         verify(engine).registerWebExtensionDelegate(delegateCaptor.capture())
 
-        delegateCaptor.value.onNewTab(ext, engineSession, false, "https://mozilla.org")
+        delegateCaptor.value.onNewTab(ext, engineSession, false, "https://mozilla.org", false)
 
         captureMiddleware.assertFirstAction(TabListAction.AddTabAction::class) { action ->
             assertEquals("https://mozilla.org", action.tab.content.url)