diff --git a/.changeset/timeline-actions-narrow-viewport.md b/.changeset/timeline-actions-narrow-viewport.md
new file mode 100644
index 00000000000..9adf82e3dc6
--- /dev/null
+++ b/.changeset/timeline-actions-narrow-viewport.md
@@ -0,0 +1,5 @@
+---
+'@primer/react': patch
+---
+
+Timeline: `Timeline.Actions` now wraps onto a new row below `Timeline.Body`, left-aligned with the body content, when `Timeline.Item` is narrower than 480px.
diff --git a/packages/react/src/Timeline/Timeline.features.stories.module.css b/packages/react/src/Timeline/Timeline.features.stories.module.css
index 475b9abf9db..d1337a60e6b 100644
--- a/packages/react/src/Timeline/Timeline.features.stories.module.css
+++ b/packages/react/src/Timeline/Timeline.features.stories.module.css
@@ -49,19 +49,31 @@
   color: var(--fgColor-muted);
 }
 
+.InlineAvatar {
+  vertical-align: middle;
+  margin-right: var(--base-size-4);
+}
+
+/* Title on top, lock icon and state pill stacked below at narrow;
+   inline row with the title claiming remaining space above 480px. */
 .CrossReferenceRow {
   display: flex;
+  flex-direction: row;
   align-items: flex-start;
   gap: var(--base-size-12);
   margin-top: var(--base-size-4);
 }
 
-.CrossReferenceContent {
-  flex: 1;
-  min-width: 0;
+@container (width < 480px) {
+  .CrossReferenceRow {
+    flex-direction: column;
+    gap: var(--base-size-4);
+  }
 }
 
 .CrossReferenceTitle {
+  flex: 1;
+  min-width: 0;
   font-size: var(--text-title-size-small);
   line-height: var(--text-title-lineHeight-small);
 }
@@ -87,18 +99,6 @@
   color: var(--fgColor-accent);
 }
 
-.CrossReferenceMeta {
-  color: var(--fgColor-muted);
-  flex-shrink: 0;
-}
-
-.CrossReferenceActions {
-  display: flex;
-  align-items: center;
-  gap: var(--base-size-12);
-  flex-shrink: 0;
-}
-
 .CrossReferenceTaskline {
   display: flex;
   align-items: center;
@@ -108,9 +108,18 @@
   color: var(--fgColor-muted);
 }
 
-.InlineAvatar {
-  vertical-align: middle;
-  margin-right: var(--base-size-4);
+.CrossReferenceMeta {
+  color: var(--fgColor-muted);
+  flex-shrink: 0;
+}
+
+/* Hides Timeline.Actions children (Verified / Unverified signature labels
+   on commit rows) when Timeline is narrow, so only the compact icon + SHA
+   cluster remains after the Actions row wraps beneath Body. */
+@container (width < 480px) {
+  .HideAtNarrow {
+    display: none;
+  }
 }
 
 .Timestamp {
diff --git a/packages/react/src/Timeline/Timeline.features.stories.tsx b/packages/react/src/Timeline/Timeline.features.stories.tsx
index 806f7b42e5c..9c930722b09 100644
--- a/packages/react/src/Timeline/Timeline.features.stories.tsx
+++ b/packages/react/src/Timeline/Timeline.features.stories.tsx
@@ -280,7 +280,7 @@ export const WithActions = () => (
           </Link>
         </Timeline.Body>
         <Timeline.Actions>
-          <Label className={classes.SignatureLabelVerified}>Verified</Label>
+          <Label className={`${classes.SignatureLabelVerified} ${classes.HideAtNarrow}`}>Verified</Label>
           <Octicon icon={CheckIcon} className={classes.IconSuccess} aria-label="All checks passed" />
           <Link href="#" className={classes.ShaLink} muted>
             3fbdc0
@@ -297,7 +297,7 @@ export const WithActions = () => (
           </Link>
         </Timeline.Body>
         <Timeline.Actions>
-          <Label>Unverified</Label>
+          <Label className={classes.HideAtNarrow}>Unverified</Label>
           <Octicon icon={XIcon} className={classes.IconDanger} aria-label="Some checks failed" />
           <Link href="#" className={classes.ShaLink} muted>
             3fbdc0
@@ -322,24 +322,20 @@ export const WithActions = () => (
             just now
           </Link>
           <div className={classes.CrossReferenceRow}>
-            <div className={classes.CrossReferenceContent}>
-              <div className={classes.CrossReferenceTitle}>
-                <Link href="#" className={classes.CrossReferenceLink}>
-                  <span className={classes.CrossReferenceName}>Fix positioning of Autocomplete overlay menu</span>{' '}
-                  <span className={classes.CrossReferenceNumber}>primer/react#7431</span>
-                </Link>
-              </div>
-              <div className={classes.CrossReferenceTaskline}>
-                <Octicon icon={TasklistIcon} size={16} />
-                17 tasks
-              </div>
-            </div>
-            <div className={classes.CrossReferenceActions}>
-              <Octicon icon={LockIcon} size={16} className={classes.CrossReferenceMeta} />
-              <StateLabel status="pullOpened" size="medium">
-                Open
-              </StateLabel>
+            <div className={classes.CrossReferenceTitle}>
+              <Link href="#" className={classes.CrossReferenceLink}>
+                <span className={classes.CrossReferenceName}>Fix positioning of Autocomplete overlay menu</span>{' '}
+                <span className={classes.CrossReferenceNumber}>primer/react#7431</span>
+              </Link>
             </div>
+            <Octicon icon={LockIcon} size={16} className={classes.CrossReferenceMeta} aria-label="Private" />
+            <StateLabel status="pullOpened" size="small">
+              Open
+            </StateLabel>
+          </div>
+          <div className={classes.CrossReferenceTaskline}>
+            <Octicon icon={TasklistIcon} size={16} />
+            17 tasks
           </div>
         </Timeline.Body>
       </Timeline.Item>
diff --git a/packages/react/src/Timeline/Timeline.module.css b/packages/react/src/Timeline/Timeline.module.css
index bbedaee66a7..340516926f5 100644
--- a/packages/react/src/Timeline/Timeline.module.css
+++ b/packages/react/src/Timeline/Timeline.module.css
@@ -4,6 +4,10 @@
   list-style: none;
   padding: 0;
   margin: 0;
+  /* Container for the narrow-viewport rules at the end of this file. Uses
+     an inline-size container so behavior tracks the timeline's own width,
+     not the viewport (works inside narrow side panels and split views). */
+  container-type: inline-size;
 
   &:where([data-clip-sidebar='start']),
   &:where([data-clip-sidebar='both']) {
@@ -194,3 +198,33 @@
   gap: var(--base-size-8);
   flex-shrink: 0;
 }
+
+/* Below 480px inline size, wrap Timeline.Actions onto its own row under
+   Timeline.Body via a 2-column grid. The badge keeps the left column so
+   the vertical rule stays consistent. */
+@container (width < 480px) {
+  .TimelineItem {
+    display: grid;
+    grid-template-columns: auto 1fr;
+    grid-template-areas:
+      'badge body'
+      '.     actions';
+  }
+
+  .TimelineBadgeWrapper {
+    grid-area: badge;
+  }
+
+  .TimelineBody {
+    grid-area: body;
+  }
+
+  .TimelineItemActions {
+    grid-area: actions;
+    /* Reset flex-row auto-push; the wrapped row sits under Body. */
+    margin-top: var(--base-size-8);
+    margin-left: 0;
+    justify-content: flex-start;
+    min-height: 0;
+  }
+}