--- a/browser/components/extensions/ext-commands.js
+++ b/browser/components/extensions/ext-commands.js
@@ -112,17 +112,17 @@ this.commands = class extends ExtensionA
    * @param {Document} doc The XUL document.
    * @param {string} name The name of the command.
    * @param {string} shortcut The shortcut provided in the manifest.
    * @see https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XUL/key
    *
    * @returns {Document} The newly created Key element.
    */
   buildKey(doc, name, shortcut) {
-    let keyElement = this.buildKeyFromShortcut(doc, shortcut);
+    let keyElement = this.buildKeyFromShortcut(doc, name, shortcut);
 
     // 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.
@@ -149,31 +149,36 @@ this.commands = class extends ExtensionA
 
     return keyElement;
   }
 
   /**
    * Builds a XUL Key element from the provided shortcut.
    *
    * @param {Document} doc The XUL document.
+   * @param {string} name The name of the shortcut.
    * @param {string} shortcut The shortcut provided in the manifest.
    *
    * @see https://developer.mozilla.org/en-US/docs/Mozilla/Tech/XUL/key
    * @returns {Document} The newly created Key element.
    */
-  buildKeyFromShortcut(doc, shortcut) {
+  buildKeyFromShortcut(doc, name, shortcut) {
     let keyElement = doc.createElementNS(XUL_NS, "key");
 
     let parts = shortcut.split("+");
 
     // The key is always the last element.
     let chromeKey = parts.pop();
 
     // The modifiers are the remaining elements.
     keyElement.setAttribute("modifiers", this.getModifiersAttribute(parts));
+    if (name == "_execute_sidebar_action") {
+      let id = `ext-key-id-${this.id}-sidebar-action`;
+      keyElement.setAttribute("id", id);
+    }
 
     if (/^[A-Z]$/.test(chromeKey)) {
       // We use the key attribute for all single digits and characters.
       keyElement.setAttribute("key", chromeKey);
     } else {
       keyElement.setAttribute("keycode", this.getKeycodeAttribute(chromeKey));
       keyElement.setAttribute("event", "keydown");
     }

--- a/browser/components/extensions/ext-sidebarAction.js
+++ b/browser/components/extensions/ext-sidebarAction.js
@@ -157,16 +157,18 @@ this.sidebarAction = class extends Exten
     // checkmarks in the menus.
     let broadcaster = document.createElementNS(XUL_NS, "broadcaster");
     broadcaster.setAttribute("id", this.id);
     broadcaster.setAttribute("autoCheck", "false");
     broadcaster.setAttribute("type", "checkbox");
     broadcaster.setAttribute("group", "sidebar");
     broadcaster.setAttribute("label", details.title);
     broadcaster.setAttribute("sidebarurl", this.sidebarUrl(details.panel));
+    let id = `ext-key-id-${this.id}`;
+    broadcaster.setAttribute("key", id);
 
     // oncommand gets attached to menuitem, so we use the observes attribute to
     // get the command id we pass to SidebarUI.
     broadcaster.setAttribute("oncommand", "SidebarUI.toggle(this.getAttribute('observes'))");
 
     let header = document.getElementById("sidebar-switcher-target");
     header.addEventListener("SidebarShown", this.updateHeader);
 

--- a/browser/components/extensions/test/browser/browser_ext_sidebarAction.js
+++ b/browser/components/extensions/test/browser/browser_ext_sidebarAction.js
@@ -1,18 +1,25 @@
 /* -*- Mode: indent-tabs-mode: nil; js-indent-level: 2 -*- */
 /* vim: set sts=2 sw=2 et tw=80: */
 "use strict";
 
 requestLongerTimeout(2);
 
 let extData = {
   manifest: {
-    "sidebar_action": {
-      "default_panel": "sidebar.html",
+    commands: {
+      _execute_sidebar_action: {
+        suggested_key: {
+          default: "Ctrl+Shift+I",
+        },
+      },
+    },
+    sidebar_action: {
+      default_panel: "sidebar.html",
     },
   },
   useAddonManager: "temporary",
 
   files: {
     "sidebar.html": `
       <!DOCTYPE html>
       <html>
@@ -105,16 +112,22 @@ add_task(async function sidebar_isOpen()
   let extension1 = ExtensionTestUtils.loadExtension(extData);
   await extension1.startup();
 
   info("Test extension1's sidebar is opened on install");
   await extension1.awaitMessage("sidebar");
   await sendMessage(extension1, "isOpen", {result: true});
   let sidebar1ID = SidebarUI.currentID;
 
+  // Test that the key is set for the extension.
+  let button = document.getElementById(`button_${makeWidgetId(extension1.id)}-sidebar-action`);
+  ok(button.hasAttribute("key"), "The menu item has a key specified");
+  let key = document.getElementById(button.getAttribute("key"));
+  ok(key, "The key attribute finds the related key element");
+
   info("Load extension2");
   let extension2 = ExtensionTestUtils.loadExtension(extData);
   await extension2.startup();
 
   info("Test extension2's sidebar is opened on install");
   await extension2.awaitMessage("sidebar");
   await sendMessage(extension1, "isOpen", {result: false});
   await sendMessage(extension2, "isOpen", {result: true});