diff --git a/toolkit/components/extensions/ext-webNavigation.js b/toolkit/components/extensions/ext-webNavigation.js
index d1a6ae820b93..4136a7f460f4 100644
--- a/toolkit/components/extensions/ext-webNavigation.js
+++ b/toolkit/components/extensions/ext-webNavigation.js
@@ -161,6 +161,7 @@ function convertGetFrameResult(tabId, data) {
 extensions.registerSchemaAPI("webNavigation", "addon_parent", context => {
   return {
     webNavigation: {
+      onTabReplaced: ignoreEvent(context, "webNavigation.onTabReplaced"),
       onBeforeNavigate: new WebNavigationEventManager(context, "onBeforeNavigate").api(),
       onCommitted: new WebNavigationEventManager(context, "onCommitted").api(),
       onDOMContentLoaded: new WebNavigationEventManager(context, "onDOMContentLoaded").api(),
diff --git a/toolkit/components/extensions/schemas/web_navigation.json b/toolkit/components/extensions/schemas/web_navigation.json
index 3bf7adeb39d0..1e13b181ace6 100644
--- a/toolkit/components/extensions/schemas/web_navigation.json
+++ b/toolkit/components/extensions/schemas/web_navigation.json
@@ -340,7 +340,6 @@
       },
       {
         "name": "onTabReplaced",
-        "unsupported": true,
         "type": "function",
         "description": "Fired when the contents of the tab is replaced by a different (usually previously pre-rendered) tab.",
         "parameters": [
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_webnavigation.html b/toolkit/components/extensions/test/mochitest/test_ext_webnavigation.html
index 32c55f295417..2287fd9b153a 100644
--- a/toolkit/components/extensions/test/mochitest/test_ext_webnavigation.html
+++ b/toolkit/components/extensions/test/mochitest/test_ext_webnavigation.html
@@ -21,6 +21,7 @@ function backgroundScript() {
   const URL = BASE + "/file_WebNavigation_page1.html";
 
   const EVENTS = [
+    "onTabReplaced",
     "onBeforeNavigate",
     "onCommitted",
     "onDOMContentLoaded",