--- a/browser/components/extensions/.eslintrc.js
+++ b/browser/components/extensions/.eslintrc.js
@@ -10,12 +10,13 @@ module.exports = {  // eslint-disable-li
     "TabContext": true,
     "Window": true,
     "WindowEventManager": true,
     "browserActionFor": true,
     "getCookieStoreIdForTab": true,
     "getDevToolsTargetForContext": true,
     "makeWidgetId": true,
     "pageActionFor": true,
+    "sidebarActionFor": true,
     "tabTracker": true,
     "windowTracker": true,
   },
 };

--- a/browser/components/extensions/ext-commands.js
+++ b/browser/components/extensions/ext-commands.js
@@ -120,26 +120,32 @@ CommandList.prototype = {
     // We need to have the attribute "oncommand" for the "command" listener to fire,
     // and it is currently ignored when set to the empty string.
     keyElement.setAttribute("oncommand", "//");
 
     /* eslint-disable mozilla/balanced-listeners */
     // We remove all references to the key elements when the extension is shutdown,
     // therefore the listeners for these elements will be garbage collected.
     keyElement.addEventListener("command", (event) => {
+      let action;
       if (name == "_execute_page_action") {
-        let win = event.target.ownerGlobal;
-        pageActionFor(this.extension).triggerAction(win);
+        action = pageActionFor(this.extension);
       } else if (name == "_execute_browser_action") {
-        let win = event.target.ownerGlobal;
-        browserActionFor(this.extension).triggerAction(win);
+        action = browserActionFor(this.extension);
+      } else if (name == "_execute_sidebar_action") {
+        action = sidebarActionFor(this.extension);
       } else {
         this.extension.tabManager
             .addActiveTabPermission();
         this.emit("command", name);
+        return;
+      }
+      if (action) {
+        let win = event.target.ownerGlobal;
+        action.triggerAction(win);
       }
     });
     /* eslint-enable mozilla/balanced-listeners */
 
     return keyElement;
   },
 
   /**

--- a/browser/components/extensions/ext-sidebarAction.js
+++ b/browser/components/extensions/ext-sidebarAction.js
@@ -247,16 +247,29 @@ class SidebarAction {
       }
       let broadcaster = document.getElementById(this.id);
       if (broadcaster) {
         broadcaster.remove();
       }
     }
     windowTracker.removeOpenListener(this.windowOpenListener);
   }
+
+  /**
+   * Triggers this sidebar action for the given window, with the same effects as
+   * if it were toggled via menu or toolbarbutton by a user.
+   *
+   * @param {ChromeWindow} window
+   */
+  triggerAction(window) {
+    let {SidebarUI} = window;
+    if (SidebarUI) {
+      SidebarUI.toggle(this.id);
+    }
+  }
 }
 
 SidebarAction.for = (extension) => {
   return sidebarActionMap.get(extension);
 };
 
 global.sidebarActionFor = SidebarAction.for;
 

--- a/browser/components/extensions/test/browser/browser-common.ini
+++ b/browser/components/extensions/test/browser/browser-common.ini
@@ -33,16 +33,17 @@ support-files =
 [browser_ext_browserAction_popup_resize.js]
 [browser_ext_browserAction_simple.js]
 [browser_ext_browsingData_formData.js]
 [browser_ext_browsingData_history.js]
 [browser_ext_browsingData_pluginData.js]
 [browser_ext_browsingData_serviceWorkers.js]
 [browser_ext_commands_execute_browser_action.js]
 [browser_ext_commands_execute_page_action.js]
+[browser_ext_commands_execute_sidebar_action.js]
 [browser_ext_commands_getAll.js]
 [browser_ext_commands_onCommand.js]
 [browser_ext_contentscript_connect.js]
 [browser_ext_contextMenus.js]
 [browser_ext_contextMenus_checkboxes.js]
 [browser_ext_contextMenus_chrome.js]
 [browser_ext_contextMenus_icons.js]
 [browser_ext_contextMenus_onclick.js]

new file mode 100644
--- /dev/null
+++ b/browser/components/extensions/test/browser/browser_ext_commands_execute_sidebar_action.js
@@ -0,0 +1,52 @@
+/* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
+/* vim: set sts=2 sw=2 et tw=80: */
+"use strict";
+
+add_task(function* test_execute_sidebar_action() {
+  let extension = ExtensionTestUtils.loadExtension({
+    manifest: {
+      "commands": {
+        "_execute_sidebar_action": {
+          "suggested_key": {
+            "default": "Alt+Shift+J",
+          },
+        },
+      },
+      "sidebar_action": {
+        "default_panel": "sidebar.html",
+      },
+    },
+    files: {
+      "sidebar.html": `
+        <!DOCTYPE html>
+        <html>
+          <head>
+            <meta charset="utf-8">
+            <script src="sidebar.js"></script>
+          </head>
+        </html>
+      `,
+
+      "sidebar.js": function() {
+        browser.runtime.sendMessage("from-sidebar-action");
+      },
+    },
+    background() {
+      browser.runtime.onMessage.addListener(msg => {
+        if (msg == "from-sidebar-action") {
+          browser.test.notifyPass("execute-sidebar-action-opened");
+        }
+      });
+    },
+  });
+
+  yield extension.startup();
+  yield SimpleTest.promiseFocus(window);
+  // Since we didn't set useAddonManager, the sidebar will not be automatically
+  // opened for this test.
+  ok(document.getElementById("sidebar-box").hidden, "sidebar box is not visible");
+  // Send the key to open the sidebar.
+  EventUtils.synthesizeKey("j", {altKey: true, shiftKey: true});
+  yield extension.awaitFinish("execute-sidebar-action-opened");
+  yield extension.unload();
+});