diff --git a/toolkit/components/extensions/Extension.jsm b/toolkit/components/extensions/Extension.jsm
index 7cf5105814bb..456a1f94f429 100644
--- a/toolkit/components/extensions/Extension.jsm
+++ b/toolkit/components/extensions/Extension.jsm
@@ -147,6 +147,7 @@ const CHILD_SHUTDOWN_TIMEOUT_MS = 8000;
 
 // Permissions that are only available to privileged extensions.
 const PRIVILEGED_PERMS = new Set([
+  "activityLog",
   "mozillaAddons",
   "geckoViewAddons",
   "telemetry",
diff --git a/toolkit/components/extensions/ext-toolkit.json b/toolkit/components/extensions/ext-toolkit.json
index 01a8f40d0679..c7d98a3c9a77 100644
--- a/toolkit/components/extensions/ext-toolkit.json
+++ b/toolkit/components/extensions/ext-toolkit.json
@@ -82,6 +82,14 @@
       ["extension"]
     ]
   },
+  "activityLog": {
+    "url": "chrome://extensions/content/parent/ext-activityLog.js",
+    "schema": "chrome://extensions/content/schemas/activity_log.json",
+    "scopes": ["addon_parent"],
+    "paths": [
+      ["activityLog"]
+    ]
+  },
   "i18n": {
     "url": "chrome://extensions/content/parent/ext-i18n.js",
     "schema": "chrome://extensions/content/schemas/i18n.json",
diff --git a/toolkit/components/extensions/jar.mn b/toolkit/components/extensions/jar.mn
index 0279d8b2e1a6..c23f5ce9d8b6 100644
--- a/toolkit/components/extensions/jar.mn
+++ b/toolkit/components/extensions/jar.mn
@@ -7,6 +7,7 @@ toolkit.jar:
     content/extensions/dummy.xul
     content/extensions/ext-browser-content.js
     content/extensions/ext-toolkit.json
+    content/extensions/parent/ext-activityLog.js (parent/ext-activityLog.js)
     content/extensions/parent/ext-alarms.js (parent/ext-alarms.js)
     content/extensions/parent/ext-backgroundPage.js (parent/ext-backgroundPage.js)
     content/extensions/parent/ext-browserSettings.js (parent/ext-browserSettings.js)
diff --git a/toolkit/components/extensions/parent/ext-activityLog.js b/toolkit/components/extensions/parent/ext-activityLog.js
new file mode 100644
index 000000000000..2cd2801199c8
--- /dev/null
+++ b/toolkit/components/extensions/parent/ext-activityLog.js
@@ -0,0 +1,38 @@
+/* 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/. */
+"use strict";
+
+ChromeUtils.defineModuleGetter(
+  this,
+  "ExtensionCommon",
+  "resource://gre/modules/ExtensionCommon.jsm"
+);
+ChromeUtils.defineModuleGetter(
+  this,
+  "ExtensionActivityLog",
+  "resource://gre/modules/ExtensionActivityLog.jsm"
+);
+
+this.activityLog = class extends ExtensionAPI {
+  getAPI(context) {
+    return {
+      activityLog: {
+        onExtensionActivity: new ExtensionCommon.EventManager({
+          context,
+          name: "activityLog.onExtensionActivity",
+          register: (fire, id) => {
+            function handler(details) {
+              fire.async(details);
+            }
+
+            ExtensionActivityLog.addListener(id, handler);
+            return () => {
+              ExtensionActivityLog.removeListener(id, handler);
+            };
+          },
+        }).api(),
+      },
+    };
+  }
+};
diff --git a/toolkit/components/extensions/schemas/activity_log.json b/toolkit/components/extensions/schemas/activity_log.json
new file mode 100644
index 000000000000..a09187ee9f80
--- /dev/null
+++ b/toolkit/components/extensions/schemas/activity_log.json
@@ -0,0 +1,87 @@
+[
+  {
+    "namespace": "manifest",
+    "types": [{
+      "$extend": "Permission",
+      "choices": [{
+        "type": "string",
+        "enum": [
+          "activityLog"
+        ]
+      }]
+    }]
+  },
+  {
+    "namespace": "activityLog",
+    "description": "Monitor extension activity",
+    "permissions": ["activityLog"],
+    "events": [
+      {
+        "name": "onExtensionActivity",
+        "description": "Receives an activityItem for each logging event.",
+        "type": "function",
+        "parameters": [
+          {
+            "name": "details",
+            "type": "object",
+            "properties": {
+              "timeStamp": {
+                "$ref": "extensionTypes.Date",
+                "description": "The date string when this call is triggered."
+              },
+              "type": {
+                "type": "string",
+                "enum": ["api_call", "api_event", "content_script", "user_script"],
+                "description": "The type of log entry.  api_call is a function call made by the extension and api_event is an event callback to the extension.  content_script is logged when a content script is injected."
+              },
+              "viewType": {
+                "type": "string",
+                "optional": true,
+                "enum": ["background", "popup", "sidebar", "tab", "devtools_page", "devtools_panel"],
+                "description": "The type of view where the activity occurred.  Content scripts will not have a viewType."
+              },
+              "name": {
+                "type": "string",
+                "description": "The name of the api call or event, or the script url if this is a content or user script event."
+              },
+              "data": {
+                "type": "object",
+                "properties": {
+                  "args": {
+                    "type": "array",
+                    "optional": true,
+                    "items": {
+                      "type": "any"
+                    },
+                    "description": "A list of arguments passed to the call."
+                  },
+                  "result": {
+                    "type": "object",
+                    "optional": true,
+                    "description": "The result of the call."
+                  },
+                  "tabId": {
+                    "type": "integer",
+                    "optional": true,
+                    "description": "The tab associated with this event if it is a tab or content script."
+                  },
+                  "url": {
+                    "type": "string",
+                    "optional": true,
+                    "description": "If the type is content_script, this is the url of the script that was injected."
+                  }
+                }
+              }
+            }
+          }
+        ],
+        "extraParameters": [
+          {
+            "name": "id",
+            "type": "string"
+          }
+        ]
+      }
+    ]
+  }
+]
diff --git a/toolkit/components/extensions/schemas/jar.mn b/toolkit/components/extensions/schemas/jar.mn
index f897860d2fa1..d66d537968d0 100644
--- a/toolkit/components/extensions/schemas/jar.mn
+++ b/toolkit/components/extensions/schemas/jar.mn
@@ -4,6 +4,7 @@
 
 toolkit.jar:
 % content extensions %content/extensions/
+    content/extensions/schemas/activity_log.json
     content/extensions/schemas/alarms.json
     content/extensions/schemas/browser_settings.json
 #ifndef ANDROID
diff --git a/toolkit/components/extensions/test/mochitest/mochitest-common.ini b/toolkit/components/extensions/test/mochitest/mochitest-common.ini
index 5b7607ab06c1..f991466a5161 100644
--- a/toolkit/components/extensions/test/mochitest/mochitest-common.ini
+++ b/toolkit/components/extensions/test/mochitest/mochitest-common.ini
@@ -61,6 +61,7 @@ prefs =
   browser.chrome.guess_favicon=true
 skip-if = toolkit == 'android' && !is_fennec
 
+[test_ext_activityLog.html]
 [test_ext_async_clipboard.html]
 skip-if = fission || toolkit == 'android' # near-permafail after landing bug 1270059: Bug 1523131
 [test_ext_background_canvas.html]
diff --git a/toolkit/components/extensions/test/mochitest/test_ext_activityLog.html b/toolkit/components/extensions/test/mochitest/test_ext_activityLog.html
new file mode 100644
index 000000000000..5561c0f23ff5
--- /dev/null
+++ b/toolkit/components/extensions/test/mochitest/test_ext_activityLog.html
@@ -0,0 +1,290 @@
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>WebExtension activityLog test</title>
+  <script src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script src="/tests/SimpleTest/ExtensionTestUtils.js"></script>
+  <script type="text/javascript" src="head.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+
+<script type="text/javascript">
+"use strict";
+
+
+add_task(async function test_api() {
+  let URL = "http://mochi.test:8888/tests/toolkit/components/extensions/test/mochitest/file_sample.html";
+
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: { gecko: { id: "watched@tests.mozilla.org" } },
+      permissions: ["webRequest", "webRequestBlocking", "<all_urls>"],
+      content_scripts: [
+        {
+          matches: ["http://mochi.test/*/file_sample.html"],
+          js: ["content_script.js"],
+          run_at: "document_idle",
+        },
+      ],
+    },
+    files: {
+      "content_script.js": () => {
+        browser.test.sendMessage("content_script");
+      },
+      "registered_script.js": () => {
+        browser.test.sendMessage("registered_script");
+      },
+    },
+    async background() {
+      async function runTest() {
+        // Test activity for a child function call.
+        browser.test.assertEq(
+          undefined,
+          browser.activityLog,
+          "activityLog requires permission"
+        );
+
+        // Test a child event manager.
+        browser.test.onMessage.addListener(async msg => {
+        });
+
+        // Test a parent event manager.
+        browser.webRequest.onBeforeRequest.addListener(
+          details => {
+            return { cancel: false };
+          },
+          { urls: ["http://mochi.test/*/file_sample.html"] },
+          ["blocking"]
+        );
+
+        // A manifest based content script is already
+        // registered, we do a dynamic registration here.
+        await browser.contentScripts.register({
+          js: [{ file: "registered_script.js" }],
+          matches: ["http://mochi.test/*/file_sample.html"],
+          runAt: "document_start",
+        });
+        browser.test.sendMessage("ready");
+      }
+      browser.test.onMessage.addListener(msg => {
+        // Logging has started here so this listener is logged, but the
+        // call adding it was not.  We do an additional onMessage.addListener
+        // call in the test function to validate child based event managers.
+        if (msg == "runtest") {
+          browser.test.assertTrue(true, msg);
+          runTest();
+        }
+      });
+      browser.test.sendMessage("url", browser.extension.getURL(""));
+    },
+  });
+
+  async function backgroundScript(expectedUrl, extensionUrl) {
+    let expecting = [
+      // Test child-only api_call.
+      {
+        type: "api_call",
+        name: "test.assertTrue",
+        data: { args: [true, "runtest"] },
+      },
+
+      // Test child-only api_call.
+      {
+        type: "api_call",
+        name: "test.assertEq",
+        data: {
+          args: [null, null, "activityLog requires permission"],
+        },
+      },
+      // Test child addListener calls.
+      {
+        type: "api_call",
+        name: "test.onMessage.addListener",
+        data: {
+          args: [],
+        },
+      },
+      // Test parent addListener calls.
+      {
+        type: "api_call",
+        name: "webRequest.onBeforeRequest.addListener",
+        data: {
+          args: [
+            {
+              incognito: null,
+              tabId: null,
+              types: null,
+              urls: ["http://mochi.test/*/file_sample.html"],
+              windowId: null,
+            },
+            ["blocking"],
+          ],
+        },
+      },
+      // Test an api that makes use of callParentAsyncFunction.
+      {
+        type: "api_call",
+        name: "contentScripts.register",
+        data: {
+          args: [
+            {
+              allFrames: null,
+              css: null,
+              excludeGlobs: null,
+              excludeMatches: null,
+              includeGlobs: null,
+              js: [
+                {
+                  file: `${extensionUrl}registered_script.js`,
+                },
+              ],
+              matchAboutBlank: null,
+              matches: ["http://mochi.test/*/file_sample.html"],
+              runAt: "document_start",
+            },
+          ],
+        },
+      },
+      // Test child api_event calls.
+      {
+        type: "api_event",
+        name: "test.onMessage",
+        data: { args: ["runtest"] },
+      },
+      {
+        type: "api_call",
+        name: "test.sendMessage",
+        data: { args: ["ready"] },
+      },
+      // Test parent api_event calls.
+      {
+        type: "api_event",
+        name: "webRequest.onBeforeRequest",
+        data: {
+          args: [
+            {
+              url: expectedUrl,
+              method: "GET",
+              type: "main_frame",
+              frameId: 0,
+              parentFrameId: -1,
+              ip: null,
+              frameAncestors: [],
+              incognito: false,
+            },
+          ],
+          result: {
+            cancel: false,
+          },
+        },
+      },
+      // Test manifest based content script.
+      {
+        type: "content_script",
+        name: "content_script.js",
+        data: { url: expectedUrl, tabId: 1 },
+      },
+      // registered script test
+      {
+        type: "content_script",
+        name: `${extensionUrl}registered_script.js`,
+        data: { url: expectedUrl, tabId: 1 },
+      },
+      {
+        type: "api_call",
+        name: "test.sendMessage",
+        data: { args: ["registered_script"], tabId: 1 },
+      },
+      {
+        type: "api_call",
+        name: "test.sendMessage",
+        data: { args: ["content_script"], tabId: 1 },
+      },
+    ];
+    browser.test.assertTrue(browser.activityLog, "activityLog is privileged");
+
+    let tab;
+    browser.activityLog.onExtensionActivity.addListener(async details => {
+      browser.test.log(`onExtensionActivity ${JSON.stringify(details)}`);
+      let test = expecting.shift();
+      if (!test) {
+        browser.test.notifyFail(`no test for ${details.name}`);
+      }
+      delete details.timeStamp;
+      // On multiple runs, tabId will be different.  Get the current tabId and
+      // use that.
+      if (test.data.tabId !== undefined) {
+        test.data.tabId = tab.id;
+      }
+
+      // hack for webRequest test
+      if (details.name === "webRequest.onBeforeRequest") {
+        // Remove items that may be variable, the important
+        // aspect is that we generally get the activity
+        // logging we expect.
+        delete details.data.args[0].requestId;
+        delete details.data.args[0].tabId;
+        delete details.data.args[0].originUrl;
+        delete details.data.args[0].timeStamp;
+        delete details.data.args[0].proxyInfo;
+      }
+
+      browser.test.assertEq(test.type, details.type, "type matches");
+      if (test.type == "content_script") {
+        browser.test.assertTrue(
+          details.name.includes(test.name),
+          "content script name matches"
+        );
+      } else {
+        browser.test.assertEq(test.name, details.name, "name matches");
+      }
+      browser.test.assertEq(
+        JSON.stringify(test.data),
+        JSON.stringify(details.data),
+        "message matches"
+      );
+      if (expecting.length == 0) {
+        await browser.tabs.remove(tab.id);
+        browser.test.notifyPass("activity");
+      }
+    }, "watched@tests.mozilla.org");
+
+    browser.test.onMessage.addListener(async msg => {
+      if (msg === "opentab") {
+        tab = await browser.tabs.create({url: expectedUrl});
+      }
+    });
+  }
+
+  await extension.startup();
+  let extensionUrl = await extension.awaitMessage("url");
+
+  let logger = ExtensionTestUtils.loadExtension({
+    isPrivileged: true,
+    manifest: {
+      applications: { gecko: { id: "watcher@tests.mozilla.org" } },
+      permissions: ["activityLog"],
+    },
+    background: `(${backgroundScript})("${URL}", "${extensionUrl}")`,
+  });
+  await logger.startup();
+  extension.sendMessage("runtest");
+  await extension.awaitMessage("ready");
+  logger.sendMessage("opentab");
+
+  await Promise.all([
+    extension.awaitMessage("content_script"),
+    extension.awaitMessage("registered_script"),
+    logger.awaitFinish("activity"),
+  ]);
+
+  await extension.unload();
+  await logger.unload();
+});
+
+
+</script>
+
+</body>
+</html>
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_activityLog.js b/toolkit/components/extensions/test/xpcshell/test_ext_activityLog.js
new file mode 100644
index 000000000000..4a23b6526461
--- /dev/null
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_activityLog.js
@@ -0,0 +1,21 @@
+"use strict";
+
+add_task(async function test_api_restricted() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      applications: {
+        gecko: { id: "activityLog-permission@tests.mozilla.org" },
+      },
+      permissions: ["activityLog"],
+    },
+    async background() {
+      browser.test.assertEq(
+        undefined,
+        browser.activityLog,
+        "activityLog is privileged"
+      );
+    },
+  });
+  await extension.startup();
+  await extension.unload();
+});
diff --git a/toolkit/components/extensions/test/xpcshell/test_ext_permissions.js b/toolkit/components/extensions/test/xpcshell/test_ext_permissions.js
index 208fc11c7dc1..c546cb10bbfa 100644
--- a/toolkit/components/extensions/test/xpcshell/test_ext_permissions.js
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_permissions.js
@@ -566,6 +566,7 @@ const GRANTED_WITHOUT_USER_PROMPT = [
   "contextMenus",
   "contextualIdentities",
   "cookies",
+  "activityLog",
   "geckoProfiler",
   "identity",
   "idle",
diff --git a/toolkit/components/extensions/test/xpcshell/xpcshell-common.ini b/toolkit/components/extensions/test/xpcshell/xpcshell-common.ini
index 6515dc0589af..3e9bcd64512e 100644
--- a/toolkit/components/extensions/test/xpcshell/xpcshell-common.ini
+++ b/toolkit/components/extensions/test/xpcshell/xpcshell-common.ini
@@ -1,5 +1,6 @@
 [test_ext_MessageManagerProxy.js]
 skip-if = os == 'android' # Bug 1545439
+[test_ext_activityLog.js]
 [test_ext_alarms.js]
 [test_ext_alarms_does_not_fire.js]
 [test_ext_alarms_periodic.js]