diff --git a/.changeset/collapsible-focus-ring.md b/.changeset/collapsible-focus-ring.md
new file mode 100644
index 000000000000..11a5d3cf6679
--- /dev/null
+++ b/.changeset/collapsible-focus-ring.md
@@ -0,0 +1,6 @@
+---
+'@astryxdesign/core': patch
+---
+
+[fix] Collapsible: the trigger button now shows a visible focus ring when focused via keyboard. The trigger's `all: unset` reset removed the browser's default outline without restoring a replacement, leaving keyboard focus invisible (WCAG 2.4.7). (#3722)
+@bhamodi
diff --git a/packages/core/src/Collapsible/Collapsible.tsx b/packages/core/src/Collapsible/Collapsible.tsx
index d41a0b50ffad..ac891dd7429e 100644
--- a/packages/core/src/Collapsible/Collapsible.tsx
+++ b/packages/core/src/Collapsible/Collapsible.tsx
@@ -64,6 +64,16 @@ const styles = stylex.create({
     color: colorVars['--color-text-primary'],
     textAlign: 'start',
     paddingBlock: 0,
+    // `all: unset` above wipes the UA focus outline; restore a keyboard-only
+    // focus ring using the standard token/offset (WCAG 2.4.7).
+    outline: {
+      default: null,
+      ':focus-visible': `2px solid ${colorVars['--color-accent']}`,
+    },
+    outlineOffset: {
+      default: '0',
+      ':focus-visible': '2px',
+    },
   },
   // Capsize: trim leading from text triggers
   triggerLabel: {