diff --git a/dom/webidl/ARIAMixin.webidl b/dom/webidl/ARIAMixin.webidl
index 2ffe1367742b..10d23af96e38 100644
--- a/dom/webidl/ARIAMixin.webidl
+++ b/dom/webidl/ARIAMixin.webidl
@@ -11,7 +11,7 @@
  */
 
 interface mixin ARIAMixin {
-  [CEReactions]
+  [Pref="accessibility.ARIAElementReflection.enabled", CEReactions]
   attribute Element? ariaActiveDescendantElement;
 
   [CEReactions, SetterThrows]
diff --git a/modules/libpref/init/StaticPrefList.yaml b/modules/libpref/init/StaticPrefList.yaml
index c9d3fd11f0ec..d4a709f90606 100644
--- a/modules/libpref/init/StaticPrefList.yaml
+++ b/modules/libpref/init/StaticPrefList.yaml
@@ -220,6 +220,11 @@
   value: false
   mirror: always
 
+- name: accessibility.ARIAElementReflection.enabled
+  type: bool
+  value: @IS_NIGHTLY_BUILD@
+  mirror: always
+
 # Whether form controls and images should be focusable with mouse, in content
 # documents.
 #
diff --git a/testing/web-platform/meta/html/dom/aria-element-reflection-disconnected.html.ini b/testing/web-platform/meta/html/dom/aria-element-reflection-disconnected.html.ini
index 889d965a0495..af62c9acb28d 100644
--- a/testing/web-platform/meta/html/dom/aria-element-reflection-disconnected.html.ini
+++ b/testing/web-platform/meta/html/dom/aria-element-reflection-disconnected.html.ini
@@ -1,4 +1,5 @@
 [aria-element-reflection-disconnected.html]
+  prefs: [accessibility.ARIAElementReflection.enabled:true]
   [Element references should stay valid when content is disconnected (element array)]
     expected: FAIL
 
diff --git a/testing/web-platform/meta/html/dom/aria-element-reflection.html.ini b/testing/web-platform/meta/html/dom/aria-element-reflection.html.ini
index 4e3d980ecdaa..ad3b5c86ed51 100644
--- a/testing/web-platform/meta/html/dom/aria-element-reflection.html.ini
+++ b/testing/web-platform/meta/html/dom/aria-element-reflection.html.ini
@@ -1,4 +1,5 @@
 [aria-element-reflection.html]
+  prefs: [accessibility.ARIAElementReflection.enabled:true]
   [aria-errormessage]
     expected: FAIL
 
diff --git a/testing/web-platform/meta/wai-aria/idlharness.window.js.ini b/testing/web-platform/meta/wai-aria/idlharness.window.js.ini
index 3c9378e157b9..01cbcd1fe8bc 100644
--- a/testing/web-platform/meta/wai-aria/idlharness.window.js.ini
+++ b/testing/web-platform/meta/wai-aria/idlharness.window.js.ini
@@ -1,4 +1,5 @@
 [idlharness.window.html]
+  prefs: [accessibility.ARIAElementReflection.enabled:true]
   [Element interface: attribute ariaControlsElements]
     expected: FAIL