--- a/toolkit/components/extensions/ext-browserSettings.js
+++ b/toolkit/components/extensions/ext-browserSettings.js
@@ -73,33 +73,43 @@ ExtensionPreferencesManager.addSetting("
     let returnObj = {};
     for (let pref of this.prefNames) {
       returnObj[pref] = value;
     }
     return returnObj;
   },
 });
 
+ExtensionPreferencesManager.addSetting("contextMenuShowEvent", {
+  prefNames: [
+    "ui.context_menus.after_mouseup",
+  ],
+
+  setCallback(value) {
+    return {[this.prefNames[0]]: value === "mouseup"};
+  },
+});
+
 ExtensionPreferencesManager.addSetting("imageAnimationBehavior", {
   prefNames: [
     "image.animation_mode",
   ],
 
   setCallback(value) {
     return {[this.prefNames[0]]: value};
   },
 });
 
-ExtensionPreferencesManager.addSetting("contextMenuShowEvent", {
+ExtensionPreferencesManager.addSetting("openBookmarksInNewTabs", {
   prefNames: [
-    "ui.context_menus.after_mouseup",
+    "browser.tabs.loadBookmarksInTabs",
   ],
 
   setCallback(value) {
-    return {[this.prefNames[0]]: value === "mouseup"};
+    return {[this.prefNames[0]]: value};
   },
 });
 
 ExtensionPreferencesManager.addSetting("webNotificationsDisabled", {
   prefNames: [
     "permissions.default.desktop-notification",
   ],
 
@@ -119,32 +129,16 @@ this.browserSettings = class extends Ext
             return Services.prefs.getCharPref("dom.popup_allowed_events") != "";
           }),
         cacheEnabled: getSettingsAPI(extension,
           "cacheEnabled",
           () => {
             return Services.prefs.getBoolPref("browser.cache.disk.enable") &&
               Services.prefs.getBoolPref("browser.cache.memory.enable");
           }),
-        homepageOverride: getSettingsAPI(extension,
-          HOMEPAGE_OVERRIDE_SETTING,
-          () => {
-            return Services.prefs.getComplexValue(
-              HOMEPAGE_URL_PREF, Ci.nsIPrefLocalizedString).data;
-          }, undefined, true),
-        imageAnimationBehavior: getSettingsAPI(extension,
-          "imageAnimationBehavior",
-          () => {
-            return Services.prefs.getCharPref("image.animation_mode");
-          }),
-        newTabPageOverride: getSettingsAPI(extension,
-          NEW_TAB_OVERRIDE_SETTING,
-          () => {
-            return aboutNewTabService.newTabURL;
-          }, URL_STORE_TYPE, true),
         contextMenuShowEvent: Object.assign(
           getSettingsAPI(
             extension,
             "contextMenuShowEvent",
             () => {
               if (AppConstants.platform === "win") {
                 return "mouseup";
               }
@@ -164,16 +158,37 @@ this.browserSettings = class extends Ext
                    details.value === "mousedown")) {
                 return false;
               }
               return ExtensionPreferencesManager.setSetting(
                 extension.id, "contextMenuShowEvent", details.value);
             },
           }
         ),
+        homepageOverride: getSettingsAPI(extension,
+          HOMEPAGE_OVERRIDE_SETTING,
+          () => {
+            return Services.prefs.getComplexValue(
+              HOMEPAGE_URL_PREF, Ci.nsIPrefLocalizedString).data;
+          }, undefined, true),
+        imageAnimationBehavior: getSettingsAPI(extension,
+          "imageAnimationBehavior",
+          () => {
+            return Services.prefs.getCharPref("image.animation_mode");
+          }),
+        newTabPageOverride: getSettingsAPI(extension,
+          NEW_TAB_OVERRIDE_SETTING,
+          () => {
+            return aboutNewTabService.newTabURL;
+          }, URL_STORE_TYPE, true),
+        openBookmarksInNewTabs: getSettingsAPI(extension,
+          "openBookmarksInNewTabs",
+          () => {
+            return Services.prefs.getBoolPref("browser.tabs.loadBookmarksInTabs");
+          }),
         webNotificationsDisabled: getSettingsAPI(extension,
           "webNotificationsDisabled",
           () => {
             let prefValue =
               Services.prefs.getIntPref(
                 "permissions.default.desktop-notification", null);
             return prefValue === PERM_DENY_ACTION;
           }),

--- a/toolkit/components/extensions/schemas/browser_settings.json
+++ b/toolkit/components/extensions/schemas/browser_settings.json
@@ -39,31 +39,35 @@
       "allowPopupsForUserEvents": {
         "$ref": "types.Setting",
         "description": "Allows or disallows pop-up windows from opening in response to user events."
       },
       "cacheEnabled": {
         "$ref": "types.Setting",
         "description": "Enables or disables the browser cache."
       },
+      "contextMenuShowEvent": {
+        "$ref": "types.Setting",
+        "description": "Controls after which mouse event context menus popup. This setting's value is of type ContextMenuMouseEvent, which has possible values of <code>mouseup</code> and <code>mousedown</code>."
+      },
       "homepageOverride": {
         "$ref": "types.Setting",
         "description": "Returns the value of the overridden home page. Read-only."
       },
       "imageAnimationBehavior": {
         "$ref": "types.Setting",
         "description": "Controls the behaviour of image animation in the browser. This setting's value is of type ImageAnimationBehavior, defaulting to <code>normal</code>."
       },
       "newTabPageOverride": {
         "$ref": "types.Setting",
         "description": "Returns the value of the overridden new tab page. Read-only."
       },
-      "contextMenuShowEvent": {
+      "openBookmarksInNewTabs": {
         "$ref": "types.Setting",
-        "description": "Controls after which mouse event context menus popup. This setting's value is of type ContextMenuMouseEvent, which has possible values of <code>mouseup</code> and <code>mousedown</code>."
+        "description": "This boolean setting controls whether bookmarks are opened in the current tab or in a new tab."
       },
       "webNotificationsDisabled": {
         "$ref": "types.Setting",
         "description": "Disables webAPI notifications."
       }
     }
   }
 ]

--- a/toolkit/components/extensions/test/xpcshell/test_ext_browserSettings.js
+++ b/toolkit/components/extensions/test/xpcshell/test_ext_browserSettings.js
@@ -24,16 +24,17 @@ add_task(async function test_browser_set
   // Create an object to hold the values to which we will initialize the prefs.
   const PREFS = {
     "browser.cache.disk.enable": true,
     "browser.cache.memory.enable": true,
     "dom.popup_allowed_events": Preferences.get("dom.popup_allowed_events"),
     "image.animation_mode": "none",
     "permissions.default.desktop-notification": PERM_UNKNOWN_ACTION,
     "ui.context_menus.after_mouseup": false,
+    "browser.tabs.loadBookmarksInTabs": false,
   };
 
   async function background() {
     browser.test.onMessage.addListener(async (msg, apiName, value) => {
       let apiObj = browser.browserSettings[apiName];
       let result = await apiObj.set({value});
       if (msg === "set") {
         browser.test.assertTrue(result, "set returns true.");
@@ -140,16 +141,23 @@ add_task(async function test_browser_set
     await testNoOpSetting("contextMenuShowEvent", "mousedown",
       {"ui.context_menus.after_mouseup": AppConstants.platform === "win"});
   } else {
     await testSetting(
       "contextMenuShowEvent", "mousedown",
       {"ui.context_menus.after_mouseup": false});
   }
 
+  await testSetting(
+    "openBookmarksInNewTabs", true,
+    {"browser.tabs.loadBookmarksInTabs": true});
+  await testSetting(
+    "openBookmarksInNewTabs", false,
+    {"browser.tabs.loadBookmarksInTabs": false});
+
   await extension.unload();
   await promiseShutdownManager();
 });
 
 add_task(async function test_bad_value() {
   async function background() {
     await browser.test.assertRejects(
       browser.browserSettings.contextMenuShowEvent.set({value: "bad"}),