diff --git a/.changeset/chatty-paws-attend.md b/.changeset/chatty-paws-attend.md
new file mode 100644
index 00000000000..2deee72b523
--- /dev/null
+++ b/.changeset/chatty-paws-attend.md
@@ -0,0 +1,5 @@
+---
+'@primer/react': patch
+---
+
+Add keyboard-accessible tooltip for truncated ActionList.Description
diff --git a/packages/react/src/ActionList/ActionList.test.tsx b/packages/react/src/ActionList/ActionList.test.tsx
index c7d58780488..c3afff40a1f 100644
--- a/packages/react/src/ActionList/ActionList.test.tsx
+++ b/packages/react/src/ActionList/ActionList.test.tsx
@@ -168,8 +168,10 @@ describe('ActionList', () => {
 
     const descriptions = container.querySelectorAll('[data-component="ActionList.Description"]')
 
-    expect(descriptions[0]).toHaveAttribute('title', 'Simple string description')
-    expect(descriptions[1]).toHaveAttribute('title', 'Complex content')
+    // For button-semantic items, the native title is suppressed in favor of
+    // a keyboard-accessible Tooltip rendered by the parent Item.
+    expect(descriptions[0]).toHaveAttribute('title', '')
+    expect(descriptions[1]).toHaveAttribute('title', '')
     expect(descriptions[2]).not.toHaveAttribute('title')
   })
 
diff --git a/packages/react/src/ActionList/Description.test.tsx b/packages/react/src/ActionList/Description.test.tsx
index a0aabe3bcd5..5312364912e 100644
--- a/packages/react/src/ActionList/Description.test.tsx
+++ b/packages/react/src/ActionList/Description.test.tsx
@@ -32,7 +32,9 @@ describe('ActionList.Description', () => {
 
     const description = getByText('Item 1 description')
     expect(description.tagName).toBe('DIV')
-    expect(description).toHaveAttribute('title', 'Item 1 description')
+    // For button-semantic items, the native title is suppressed in favor of
+    // a keyboard-accessible Tooltip rendered by the parent Item.
+    expect(description).toHaveAttribute('title', '')
     expect(description).toHaveStyle('flex-basis: auto')
     expect(description).toHaveStyle('text-overflow: ellipsis')
     expect(description).toHaveStyle('overflow: hidden')
diff --git a/packages/react/src/ActionList/Description.tsx b/packages/react/src/ActionList/Description.tsx
index dc21f933387..20c37100e0b 100644
--- a/packages/react/src/ActionList/Description.tsx
+++ b/packages/react/src/ActionList/Description.tsx
@@ -29,7 +29,7 @@ export const Description: FCWithSlotMarker<React.PropsWithChildren<ActionListDes
   style,
   ...props
 }) => {
-  const {blockDescriptionId, inlineDescriptionId} = React.useContext(ItemContext)
+  const {blockDescriptionId, inlineDescriptionId, setTruncatedText} = React.useContext(ItemContext)
   const containerRef = React.useRef<HTMLDivElement>(null)
   const [computedTitle, setComputedTitle] = React.useState<string>('')
 
@@ -43,6 +43,29 @@ export const Description: FCWithSlotMarker<React.PropsWithChildren<ActionListDes
 
   const effectiveTitle = typeof props.children === 'string' ? props.children : computedTitle
 
+  // Detect truncation and signal to parent Item for Tooltip
+  React.useEffect(() => {
+    if (!truncate || !containerRef.current || !setTruncatedText) return
+
+    function isContentTruncated() {
+      const el = containerRef.current
+      if (!el) return false
+      return el.scrollWidth > el.clientWidth
+    }
+
+    // Check initially
+    setTruncatedText(isContentTruncated() ? effectiveTitle : undefined)
+
+    const observer = new ResizeObserver(() => {
+      setTruncatedText(isContentTruncated() ? effectiveTitle : undefined)
+    })
+    observer.observe(containerRef.current)
+
+    return () => {
+      observer.disconnect()
+    }
+  }, [truncate, effectiveTitle, setTruncatedText])
+
   if (variant === 'block' || !truncate) {
     return (
       <span
@@ -61,7 +84,7 @@ export const Description: FCWithSlotMarker<React.PropsWithChildren<ActionListDes
         id={inlineDescriptionId}
         className={clsx(className, classes.Description)}
         style={style}
-        title={effectiveTitle}
+        title={setTruncatedText ? '' : effectiveTitle}
         inline={true}
         maxWidth="100%"
         data-component="ActionList.Description"
diff --git a/packages/react/src/ActionList/Item.tsx b/packages/react/src/ActionList/Item.tsx
index ac917743fd5..9b44317a9d4 100644
--- a/packages/react/src/ActionList/Item.tsx
+++ b/packages/react/src/ActionList/Item.tsx
@@ -16,11 +16,37 @@ import VisuallyHidden from '../_VisuallyHidden'
 import classes from './ActionList.module.css'
 import {clsx} from 'clsx'
 import {fixedForwardRef} from '../utils/modern-polymorphic'
+import {Tooltip} from '../TooltipV2'
+import {TooltipContext} from '../TooltipV2/Tooltip'
 
 type ActionListSubItemProps = {
   children?: React.ReactNode
 }
 
+/**
+ * Stable wrapper that keeps Tooltip in the tree for button-semantic items
+ * to avoid remount cycles when truncation state changes.
+ * For non-button-semantic items, renders children directly.
+ */
+function ConditionalTooltip({
+  text,
+  enabled,
+  children,
+}: {
+  text: string | undefined
+  enabled: boolean
+  children: React.ReactElement
+}) {
+  if (!enabled) {
+    return children
+  }
+  return (
+    <Tooltip text={text || ''} direction="e" delay="medium" _privateDisableTooltip={!text}>
+      {children}
+    </Tooltip>
+  )
+}
+
 export const SubItem: React.FC<ActionListSubItemProps> = ({children}) => {
   return <>{children}</>
 }
@@ -185,6 +211,8 @@ const UnwrappedItem = <As extends React.ElementType = 'li'>(
   const trailingVisualId = `${itemId}--trailing-visual`
   const inactiveWarningId = inactive && !showInactiveIndicator ? `${itemId}--warning-message` : undefined
 
+  const [truncatedText, setTruncatedText] = React.useState<string | undefined>(undefined)
+
   const DefaultItemWrapper = listSemantics ? DivItemContainerNoBox : ButtonItemContainerNoBox
 
   const ItemWrapper = _PrivateItemWrapper || DefaultItemWrapper
@@ -248,74 +276,81 @@ const UnwrappedItem = <As extends React.ElementType = 'li'>(
         inlineDescriptionId,
         blockDescriptionId,
         trailingVisualId,
+        setTruncatedText: buttonSemantics ? setTruncatedText : undefined,
       }}
     >
-      <li
-        {...containerProps}
-        ref={listSemantics ? forwardedRef : null}
-        data-variant={variant === 'danger' ? variant : undefined}
-        data-active={active ? true : undefined}
-        data-inactive={inactiveText ? true : undefined}
-        data-has-subitem={slots.subItem ? true : undefined}
-        data-has-description={slots.description ? true : false}
-        className={clsx(classes.ActionListItem, className)}
-      >
-        <ItemWrapper
-          {...wrapperProps}
-          className={classes.ActionListContent}
-          data-size={size}
-          // @ts-ignore: ItemWrapper is polymorphic and the ref type depends on the rendered element ('button' or 'li')
-          ref={forwardedRef}
+      <ConditionalTooltip text={truncatedText} enabled={buttonSemantics}>
+        <li
+          {...containerProps}
+          ref={listSemantics ? forwardedRef : null}
+          data-variant={variant === 'danger' ? variant : undefined}
+          data-active={active ? true : undefined}
+          data-inactive={inactiveText ? true : undefined}
+          data-has-subitem={slots.subItem ? true : undefined}
+          data-has-description={slots.description ? true : false}
+          className={clsx(classes.ActionListItem, className)}
         >
-          <span className={classes.Spacer} />
-          <Selection selected={selected} className={classes.LeadingAction} />
-          <VisualOrIndicator
-            inactiveText={showInactiveIndicator ? inactiveText : undefined}
-            itemHasLeadingVisual={Boolean(slots.leadingVisual)}
-            labelId={labelId}
-            loading={loading}
-            position="leading"
-          >
-            {slots.leadingVisual}
-          </VisualOrIndicator>
-          <span className={classes.ActionListSubContent} data-component="ActionList.Item--DividerContainer">
-            <ConditionalWrapper
-              if={!!slots.description}
-              className={classes.ItemDescriptionWrap}
-              data-description-variant={descriptionVariant}
+          {/* Reset TooltipContext so that child components (e.g. IconButton inside TrailingAction)
+              don't detect the outer ConditionalTooltip and suppress their own internal tooltips. */}
+          <TooltipContext.Provider value={{}}>
+            <ItemWrapper
+              {...wrapperProps}
+              className={classes.ActionListContent}
+              data-size={size}
+              // @ts-ignore: ItemWrapper is polymorphic and the ref type depends on the rendered element ('button' or 'li')
+              ref={forwardedRef}
             >
-              <span id={labelId} className={classes.ItemLabel}>
-                {childrenWithoutSlots}
-                {/* Loading message needs to be in here so it is read with the label */}
-                {/* If the item is inactive, we do not simultaneously announce that it is loading */}
-                {loading === true && !inactive && <VisuallyHidden>Loading</VisuallyHidden>}
+              <span className={classes.Spacer} />
+              <Selection selected={selected} className={classes.LeadingAction} />
+              <VisualOrIndicator
+                inactiveText={showInactiveIndicator ? inactiveText : undefined}
+                itemHasLeadingVisual={Boolean(slots.leadingVisual)}
+                labelId={labelId}
+                loading={loading}
+                position="leading"
+              >
+                {slots.leadingVisual}
+              </VisualOrIndicator>
+              <span className={classes.ActionListSubContent} data-component="ActionList.Item--DividerContainer">
+                <ConditionalWrapper
+                  if={!!slots.description}
+                  className={classes.ItemDescriptionWrap}
+                  data-description-variant={descriptionVariant}
+                >
+                  <span id={labelId} className={classes.ItemLabel}>
+                    {childrenWithoutSlots}
+                    {/* Loading message needs to be in here so it is read with the label */}
+                    {/* If the item is inactive, we do not simultaneously announce that it is loading */}
+                    {loading === true && !inactive && <VisuallyHidden>Loading</VisuallyHidden>}
+                  </span>
+                  {slots.description}
+                </ConditionalWrapper>
+                <VisualOrIndicator
+                  inactiveText={showInactiveIndicator ? inactiveText : undefined}
+                  itemHasLeadingVisual={Boolean(slots.leadingVisual)}
+                  labelId={labelId}
+                  loading={loading}
+                  position="trailing"
+                >
+                  {trailingVisual}
+                </VisualOrIndicator>
+
+                {
+                  // If the item is inactive, but it's not in an overlay (e.g. ActionMenu, SelectPanel),
+                  // render the inactive warning message directly in the item.
+                  !showInactiveIndicator && inactiveText ? (
+                    <span className={classes.InactiveWarning} id={inactiveWarningId}>
+                      {inactiveText}
+                    </span>
+                  ) : null
+                }
               </span>
-              {slots.description}
-            </ConditionalWrapper>
-            <VisualOrIndicator
-              inactiveText={showInactiveIndicator ? inactiveText : undefined}
-              itemHasLeadingVisual={Boolean(slots.leadingVisual)}
-              labelId={labelId}
-              loading={loading}
-              position="trailing"
-            >
-              {trailingVisual}
-            </VisualOrIndicator>
-
-            {
-              // If the item is inactive, but it's not in an overlay (e.g. ActionMenu, SelectPanel),
-              // render the inactive warning message directly in the item.
-              !showInactiveIndicator && inactiveText ? (
-                <span className={classes.InactiveWarning} id={inactiveWarningId}>
-                  {inactiveText}
-                </span>
-              ) : null
-            }
-          </span>
-        </ItemWrapper>
-        {!inactive && !loading && !menuContext && Boolean(slots.trailingAction) && slots.trailingAction}
-        {slots.subItem}
-      </li>
+            </ItemWrapper>
+            {!inactive && !loading && !menuContext && Boolean(slots.trailingAction) && slots.trailingAction}
+            {slots.subItem}
+          </TooltipContext.Provider>
+        </li>
+      </ConditionalTooltip>
     </ItemContext.Provider>
   )
 }
diff --git a/packages/react/src/ActionList/shared.ts b/packages/react/src/ActionList/shared.ts
index f652cf1b19c..af98c9cd30a 100644
--- a/packages/react/src/ActionList/shared.ts
+++ b/packages/react/src/ActionList/shared.ts
@@ -85,6 +85,7 @@ export type ItemContext = Pick<ActionListItemProps<React.ElementType>, 'variant'
   blockDescriptionId?: string
   trailingVisualId?: string
   inactive?: boolean
+  setTruncatedText?: (text: string | undefined) => void
 }
 
 export const ItemContext = React.createContext<ItemContext>({})