--- a/devtools/client/aboutdebugging-new/src/components/DebugTargetsPane.js
+++ b/devtools/client/aboutdebugging-new/src/components/DebugTargetsPane.js
@@ -90,22 +90,24 @@ class DebugTargetsPane extends PureCompo
       {
         className: "debug-targets-pane",
       },
       RuntimeInfo({ info }),
       DebugTargetList({
         className: "debug-target-list--temporary-extensions",
         debugTargetItemComponent: ExtensionItem,
         debugTargets: temporaryExtensions,
+        runtime,
         title: "Temporary Extensions",
       }),
       DebugTargetList({
         className: "debug-target-list--installed-extensions",
         debugTargetItemComponent: ExtensionItem,
         debugTargets: installedExtensions,
+        runtime,
         title: "Extensions",
       }),
       DebugTargetList({
         className: "debug-target-list--tabs",
         debugTargetItemComponent: TabItem,
         debugTargets: tabs,
         runtime,
         title: "Tabs",

--- a/devtools/client/aboutdebugging-new/src/components/debugtarget/ExtensionItem.js
+++ b/devtools/client/aboutdebugging-new/src/components/debugtarget/ExtensionItem.js
@@ -14,31 +14,42 @@ class ExtensionItem extends DebugTargetI
     return debugTarget.iconURL || "chrome://mozapps/skin/extensions/extensionGeneric.svg";
   }
 
   getName() {
     const { debugTarget } = this.props;
     return debugTarget.name;
   }
 
+  inspect() {
+    const { debugTarget, runtime } = this.props;
+    runtime.inspectExtension(debugTarget);
+  }
+
   parseFileUri(url) {
     // Strip a leading slash from Windows drive letter URIs.
     // file:///home/foo ~> /home/foo
     // file:///C:/foo ~> C:/foo
     const windowsRegex = /^file:\/\/\/([a-zA-Z]:\/.*)/;
 
     if (windowsRegex.test(url)) {
       return windowsRegex.exec(url)[1];
     }
 
     return url.slice("file://".length);
   }
 
   renderActionComponents() {
-    return null;
+    return dom.button(
+      {
+        className: "debug-target-item__actions__extension-inspect",
+        onClick: e => this.inspect(),
+      },
+      "Inspect"
+    );
   }
 
   renderDetailComponents() {
     return dom.div(
       {
         className: "debug-target-item__info__detail__extension",
       },
       this.renderFilePath(),

--- a/devtools/client/aboutdebugging-new/src/runtimes/runtime.js
+++ b/devtools/client/aboutdebugging-new/src/runtimes/runtime.js
@@ -56,16 +56,25 @@ class Runtime {
    * Subclass should override this method.
    * @return {Array}
    */
   async getTabs() {
     throw new Error("Subclass of Runtime should override getTabs()");
   }
 
   /**
+   * Inspect the provided extension target which can get by getExtensions().
+   * Subclass should override this method.
+   * @param {Object} - debug target
+   */
+  async inspectExtension(_) {
+    throw new Error("Subclass of Runtime should override inspectExtension()");
+  }
+
+  /**
    * Inspect the provided tab target which can get by getTabs().
    * Subclass should override this method.
    * @param {Object} - debug target
    */
   async inspectTab(_) {
     throw new Error("Subclass of Runtime should override inspectTab()");
   }
 

--- a/devtools/client/aboutdebugging-new/src/runtimes/this-firefox.js
+++ b/devtools/client/aboutdebugging-new/src/runtimes/this-firefox.js
@@ -1,14 +1,16 @@
 /* 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";
 
+const { BrowserToolboxProcess } =
+  require("resource://devtools/client/framework/ToolboxProcess.jsm");
 const { DebuggerClient } = require("devtools/shared/client/debugger-client");
 const { DebuggerServer } = require("devtools/server/main");
 const Services = require("Services");
 
 const Runtime = require("./runtime");
 
 /**
  * This class represents the Firefox instance which runs in the same environment that
@@ -41,16 +43,30 @@ class ThisFirefox extends Runtime {
     };
   }
 
   async getTabs() {
     const { tabs } = await this.client.listTabs({ favicons: true });
     return tabs;
   }
 
+  async inspectExtension(debugTarget) {
+    // Close previous addon debugging toolbox.
+    if (this.browserToolboxProcess) {
+      this.browserToolboxProcess.close();
+    }
+
+    this.browserToolboxProcess = BrowserToolboxProcess.init({
+      addonID: debugTarget.id,
+      onClose: () => {
+        this.browserToolboxProcess = null;
+      }
+    });
+  }
+
   async inspectTab(debugTarget) {
     window.open(`about:devtools-toolbox?type=tab&id=${ debugTarget.outerWindowID }`);
   }
 
   removeTabsUpdateListener(listener) {
     this.client.removeListener("tabListChanged", listener);
   }
 }