diff --git a/.changeset/chatty-phones-admire.md b/.changeset/chatty-phones-admire.md
new file mode 100644
index 00000000000..05065698a5c
--- /dev/null
+++ b/.changeset/chatty-phones-admire.md
@@ -0,0 +1,5 @@
+---
+'@primer/react': patch
+---
+
+Adds full `aria-expanded` (true/false) state to `AnchoredOverlay`, and components that consume it
diff --git a/packages/react/src/AnchoredOverlay/AnchoredOverlay.tsx b/packages/react/src/AnchoredOverlay/AnchoredOverlay.tsx
index cc6dd041cdc..f7d60df9d6b 100644
--- a/packages/react/src/AnchoredOverlay/AnchoredOverlay.tsx
+++ b/packages/react/src/AnchoredOverlay/AnchoredOverlay.tsx
@@ -172,7 +172,7 @@ export const AnchoredOverlay: React.FC<React.PropsWithChildren<AnchoredOverlayPr
           ref: anchorRef,
           id: anchorId,
           'aria-haspopup': 'true',
-          'aria-expanded': open ? 'true' : undefined,
+          'aria-expanded': open,
           tabIndex: 0,
           onClick: onAnchorClick,
           onKeyDown: onAnchorKeyDown,