--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -950,16 +950,19 @@ pref("browser.sessionstore.debug.no_auto
 // Forget closed windows/tabs after two weeks
 pref("browser.sessionstore.cleanup.forget_closed_after", 1209600000);
 // Amount of failed SessionFile writes until we restart the worker.
 pref("browser.sessionstore.max_write_failures", 5);
 
 // Whether to warn the user when quitting, even though their tabs will be restored.
 pref("browser.sessionstore.warnOnQuit", false);
 
+// Don't quit the browser when Ctrl + Q is pressed.
+pref("browser.quitShortcut.disabled", false);
+
 // allow META refresh by default
 pref("accessibility.blockautorefresh", false);
 
 // Whether history is enabled or not.
 pref("places.history.enabled", true);
 
 // Whether or not diacritics must match in history text searches.
 pref("places.search.matchDiacritics", false);

--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -1874,16 +1874,25 @@ var gBrowserInit = {
 
     if (!PrivateBrowsingUtils.enabled) {
       document.getElementById("Tools:PrivateBrowsing").hidden = true;
       // Setting disabled doesn't disable the shortcut, so we just remove
       // the keybinding.
       document.getElementById("key_privatebrowsing").remove();
     }
 
+    if (BrowserUIUtils.quitShortcutDisabled) {
+      document.getElementById("key_quitApplication").remove();
+      document.getElementById("menu_FileQuitItem").removeAttribute("key");
+      PanelMultiView.getViewNode(
+        document,
+        "appMenu-quit-button"
+      )?.removeAttribute("key");
+    }
+
     this._loadHandled = true;
   },
 
   _cancelDelayedStartup() {
     window.removeEventListener("MozAfterPaint", this._boundDelayedStartup);
     this._boundDelayedStartup = null;
   },
 

--- a/browser/base/content/nonbrowser-mac.js
+++ b/browser/base/content/nonbrowser-mac.js
@@ -105,16 +105,20 @@ function nonBrowserWindowStartup() {
 
     // Hide menuitems that don't apply to private contexts.
     if (PrivateBrowsingUtils.permanentPrivateBrowsing) {
       document.getElementById("macDockMenuNewWindow").hidden = true;
     }
     if (!PrivateBrowsingUtils.enabled) {
       document.getElementById("macDockMenuNewPrivateWindow").hidden = true;
     }
+    if (BrowserUIUtils.quitShortcutDisabled) {
+      document.getElementById("key_quitApplication").remove();
+      document.getElementById("menu_FileQuitItem").removeAttribute("key");
+    }
   }
 
   delayedStartupTimeoutId = setTimeout(nonBrowserWindowDelayedStartup, 0);
 }
 
 function nonBrowserWindowDelayedStartup() {
   delayedStartupTimeoutId = null;
 

--- a/browser/components/tests/browser/browser.ini
+++ b/browser/components/tests/browser/browser.ini
@@ -2,8 +2,9 @@
 
 [browser_bug538331.js]
 skip-if = !updater
 reason = test depends on update channel
 [browser_contentpermissionprompt.js]
 [browser_default_bookmark_toolbar_visibility.js]
 [browser_initial_tab_remoteType.js]
 [browser_startup_homepage.js]
+[browser_quit_disabled.js]

new file mode 100644
--- /dev/null
+++ b/browser/components/tests/browser/browser_quit_disabled.js
@@ -0,0 +1,58 @@
+/* Any copyright is dedicated to the Public Domain.
+ * http://creativecommons.org/publicdomain/zero/1.0/ */
+
+add_task(async function test_appMenu_quit_disabled() {
+  await SpecialPowers.pushPrefEnv({
+    set: [["browser.quitShortcut.disabled", true]],
+  });
+
+  let win = await BrowserTestUtils.openNewBrowserWindow();
+  let doc = win.document;
+
+  let menuButton = doc.getElementById("PanelUI-menu-button");
+  menuButton.click();
+  await BrowserTestUtils.waitForEvent(win.PanelUI.mainView, "ViewShown");
+
+  let quitButton = doc.querySelector(`[key="key_quitApplication"]`);
+  is(quitButton, null, "No quit button with shortcut key");
+
+  await BrowserTestUtils.closeWindow(win);
+
+  await SpecialPowers.popPrefEnv();
+});
+
+add_task(async function test_quit_shortcut_disabled() {
+  async function testQuitShortcut(shouldQuit) {
+    let win = await BrowserTestUtils.openNewBrowserWindow();
+
+    let observer = {
+      observe(subject, topic, data) {
+        is(topic, "quit-application-requested", "Right observer topic");
+        ok(shouldQuit, "Quit shortcut should NOT have worked");
+
+        // Don't actually quit the browser when testing.
+        let cancelQuit = subject.QueryInterface(Ci.nsISupportsPRBool);
+        cancelQuit.data = true;
+      },
+    };
+    Services.obs.addObserver(observer, "quit-application-requested");
+
+    let modifiers = { accelKey: true };
+    if (AppConstants.platform == "win") {
+      modifiers.shiftKey = true;
+    }
+    EventUtils.synthesizeKey("q", modifiers, win);
+
+    await BrowserTestUtils.closeWindow(win);
+
+    Services.obs.removeObserver(observer, "quit-application-requested");
+  }
+
+  // Quit shortcut should work when pref is not set.
+  await testQuitShortcut(true);
+
+  await SpecialPowers.pushPrefEnv({
+    set: [["browser.quitShortcut.disabled", true]],
+  });
+  await testQuitShortcut(false);
+});

--- a/browser/modules/BrowserUIUtils.jsm
+++ b/browser/modules/BrowserUIUtils.jsm
@@ -1,15 +1,19 @@
 /* -*- mode: js; indent-tabs-mode: nil; js-indent-level: 2 -*- */
 /* 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";
 
+var { XPCOMUtils } = ChromeUtils.import(
+  "resource://gre/modules/XPCOMUtils.jsm"
+);
+
 var EXPORTED_SYMBOLS = ["BrowserUIUtils"];
 
 var BrowserUIUtils = {
   /**
    * Check whether a page can be considered as 'empty', that its URI
    * reflects its origin, and that if it's loaded in a tab, that tab
    * could be considered 'empty' (e.g. like the result of opening
    * a 'blank' new tab).
@@ -197,8 +201,15 @@ var BrowserUIUtils = {
   trimURL(aURL) {
     let url = this.removeSingleTrailingSlashFromURL(aURL);
     // Remove "http://" prefix.
     return url.startsWith(this.trimURLProtocol)
       ? url.substring(this.trimURLProtocol.length)
       : url;
   },
 };
+
+XPCOMUtils.defineLazyPreferenceGetter(
+  BrowserUIUtils,
+  "quitShortcutDisabled",
+  "browser.quitShortcut.disabled",
+  false
+);