diff --git a/.changeset/healthy-laws-walk.md b/.changeset/healthy-laws-walk.md
new file mode 100644
index 00000000000..2c1b09b5a2f
--- /dev/null
+++ b/.changeset/healthy-laws-walk.md
@@ -0,0 +1,5 @@
+---
+"@primer/react": patch
+---
+
+Add gap prop to ActionBar for customizable spacing between items
diff --git a/packages/react/src/ActionBar/ActionBar.docs.json b/packages/react/src/ActionBar/ActionBar.docs.json
index 79a9c68f9f6..ca7e53e200b 100644
--- a/packages/react/src/ActionBar/ActionBar.docs.json
+++ b/packages/react/src/ActionBar/ActionBar.docs.json
@@ -34,7 +34,8 @@
     },
     {
       "name": "flush",
-      "derive": true
+      "derive": true,
+      "type": "boolean"
     },
     {
       "name": "className",
@@ -42,6 +43,13 @@
       "required": false,
       "description": "Custom className",
       "defaultValue": ""
+    },
+    {
+      "name": "gap",
+      "type": "'none' | 'condensed'",
+      "required": false,
+      "defaultValue": "'condensed'",
+      "description": "Horizontal gap scale between items (restricted to none or condensed)."
     }
   ],
   "subcomponents": [
diff --git a/packages/react/src/ActionBar/ActionBar.examples.stories.tsx b/packages/react/src/ActionBar/ActionBar.examples.stories.tsx
index d7c18e79123..2dab897a5ae 100644
--- a/packages/react/src/ActionBar/ActionBar.examples.stories.tsx
+++ b/packages/react/src/ActionBar/ActionBar.examples.stories.tsx
@@ -48,6 +48,31 @@ export const SmallActionBar = () => (
   </ActionBar>
 )
 
+export const GapScale = () => (
+  <div style={{display: 'flex', flexDirection: 'column', gap: 16}}>
+    <div>
+      <Text as="p" style={{marginBottom: 4}}>
+        gap=&quot;none&quot;
+      </Text>
+      <ActionBar aria-label="Toolbar gap none" gap="none">
+        <ActionBar.IconButton icon={BoldIcon} aria-label="Bold" />
+        <ActionBar.IconButton icon={ItalicIcon} aria-label="Italic" />
+        <ActionBar.IconButton icon={CodeIcon} aria-label="Code" />
+      </ActionBar>
+    </div>
+    <div>
+      <Text as="p" style={{marginBottom: 4}}>
+        gap=&quot;condensed&quot; (default)
+      </Text>
+      <ActionBar aria-label="Toolbar gap condensed" gap="condensed">
+        <ActionBar.IconButton icon={BoldIcon} aria-label="Bold" />
+        <ActionBar.IconButton icon={ItalicIcon} aria-label="Italic" />
+        <ActionBar.IconButton icon={CodeIcon} aria-label="Code" />
+      </ActionBar>
+    </div>
+  </div>
+)
+
 export const WithDisabledItems = () => (
   <ActionBar aria-label="Toolbar">
     <ActionBar.IconButton icon={BoldIcon} aria-label="Bold"></ActionBar.IconButton>
diff --git a/packages/react/src/ActionBar/ActionBar.module.css b/packages/react/src/ActionBar/ActionBar.module.css
index d795c7b57a8..305b067d3fe 100644
--- a/packages/react/src/ActionBar/ActionBar.module.css
+++ b/packages/react/src/ActionBar/ActionBar.module.css
@@ -9,7 +9,16 @@
   white-space: nowrap;
   list-style: none;
   align-items: center;
-  gap: var(--base-size-8);
+  gap: var(--actionbar-gap, var(--stack-gap-condensed));
+
+  /* Gap scale (mirrors Stack) */
+  &:where([data-gap='none']) {
+    --actionbar-gap: 0;
+  }
+
+  &:where([data-gap='condensed']) {
+    --actionbar-gap: var(--stack-gap-condensed);
+  }
 }
 
 .Nav {
diff --git a/packages/react/src/ActionBar/ActionBar.stories.tsx b/packages/react/src/ActionBar/ActionBar.stories.tsx
index 53a7d6bc956..06cb18045dd 100644
--- a/packages/react/src/ActionBar/ActionBar.stories.tsx
+++ b/packages/react/src/ActionBar/ActionBar.stories.tsx
@@ -42,10 +42,17 @@ Playground.argTypes = {
       type: 'boolean',
     },
   },
+  gap: {
+    control: {type: 'radio'},
+    options: ['none', 'condensed'],
+    description: 'Horizontal gap scale between items',
+    table: {defaultValue: {summary: 'condensed'}},
+  },
 }
 Playground.args = {
   size: 'medium',
   flush: false,
+  gap: 'condensed',
 }
 
 export const Default = () => (
diff --git a/packages/react/src/ActionBar/ActionBar.test.tsx b/packages/react/src/ActionBar/ActionBar.test.tsx
index 21139a9cb8e..c2ba761acda 100644
--- a/packages/react/src/ActionBar/ActionBar.test.tsx
+++ b/packages/react/src/ActionBar/ActionBar.test.tsx
@@ -234,3 +234,38 @@ describe('ActionBar Registry System', () => {
     expect(screen.queryByRole('button', {name: 'Will unmount'})).not.toBeInTheDocument()
   })
 })
+
+describe('ActionBar gap prop', () => {
+  it('defaults to condensed', () => {
+    render(
+      <ActionBar aria-label="Toolbar">
+        <ActionBar.IconButton icon={BoldIcon} aria-label="Bold" />
+        <ActionBar.IconButton icon={ItalicIcon} aria-label="Italic" />
+      </ActionBar>,
+    )
+    const toolbar = screen.getByRole('toolbar')
+    expect(toolbar).toHaveAttribute('data-gap', 'condensed')
+  })
+
+  it('applies provided gap scale (none)', () => {
+    render(
+      <ActionBar aria-label="Toolbar" gap="none">
+        <ActionBar.IconButton icon={BoldIcon} aria-label="Bold" />
+        <ActionBar.IconButton icon={ItalicIcon} aria-label="Italic" />
+      </ActionBar>,
+    )
+    const toolbar = screen.getByRole('toolbar')
+    expect(toolbar).toHaveAttribute('data-gap', 'none')
+  })
+
+  it('applies provided gap scale (condensed)', () => {
+    render(
+      <ActionBar aria-label="Toolbar" gap="condensed">
+        <ActionBar.IconButton icon={BoldIcon} aria-label="Bold" />
+        <ActionBar.IconButton icon={ItalicIcon} aria-label="Italic" />
+      </ActionBar>,
+    )
+    const toolbar = screen.getByRole('toolbar')
+    expect(toolbar).toHaveAttribute('data-gap', 'condensed')
+  })
+})
diff --git a/packages/react/src/ActionBar/ActionBar.tsx b/packages/react/src/ActionBar/ActionBar.tsx
index 6dcc34d81b7..1585a1b56c6 100644
--- a/packages/react/src/ActionBar/ActionBar.tsx
+++ b/packages/react/src/ActionBar/ActionBar.tsx
@@ -61,6 +61,8 @@ type A11yProps =
       'aria-labelledby': React.AriaAttributes['aria-labelledby']
     }
 
+type GapScale = 'none' | 'condensed'
+
 export type ActionBarProps = {
   /**
    * Size of the action bar
@@ -79,18 +81,29 @@ export type ActionBarProps = {
 
   /** Custom className */
   className?: string
+
+  /**
+   * Horizontal gap scale between items (mirrors Stack gap scale)
+   * @default 'condensed'
+   */
+  gap?: GapScale
 } & A11yProps
 
 export type ActionBarIconButtonProps = {disabled?: boolean} & IconButtonProps
 
 const MORE_BTN_WIDTH = 32
 
-const calculatePossibleItems = (registryEntries: Array<[string, ChildProps]>, navWidth: number, moreMenuWidth = 0) => {
+const calculatePossibleItems = (
+  registryEntries: Array<[string, ChildProps]>,
+  navWidth: number,
+  gap: number,
+  moreMenuWidth = 0,
+) => {
   const widthToFit = navWidth - moreMenuWidth
   let breakpoint = registryEntries.length // assume all items will fit
   let sumsOfChildWidth = 0
   for (const [index, [, child]] of registryEntries.entries()) {
-    sumsOfChildWidth += index > 0 ? child.width + ACTIONBAR_ITEM_GAP : child.width
+    sumsOfChildWidth += index > 0 ? child.width + gap : child.width
     if (sumsOfChildWidth > widthToFit) {
       breakpoint = index
       break
@@ -106,15 +119,17 @@ const getMenuItems = (
   moreMenuWidth: number,
   childRegistry: ChildRegistry,
   hasActiveMenu: boolean,
+  gap: number,
 ): Set<string> | void => {
   const registryEntries = Array.from(childRegistry).filter((entry): entry is [string, ChildProps] => entry[1] !== null)
 
   if (registryEntries.length === 0) return new Set()
-  const numberOfItemsPossible = calculatePossibleItems(registryEntries, navWidth)
+  const numberOfItemsPossible = calculatePossibleItems(registryEntries, navWidth, gap)
 
   const numberOfItemsPossibleWithMoreMenu = calculatePossibleItems(
     registryEntries,
     navWidth,
+    gap,
     moreMenuWidth || MORE_BTN_WIDTH,
   )
   const menuItems = new Set<string>()
@@ -158,8 +173,13 @@ export const ActionBar: React.FC<React.PropsWithChildren<ActionBarProps>> = prop
     'aria-labelledby': ariaLabelledBy,
     flush = false,
     className,
+    gap = 'condensed',
   } = props
 
+  // We derive the numeric gap from computed style so layout math stays in sync with CSS
+  const listRef = useRef<HTMLDivElement>(null)
+  const [computedGap, setComputedGap] = useState<number>(ACTIONBAR_ITEM_GAP)
+
   const [childRegistry, setChildRegistry] = useState<ChildRegistry>(() => new Map())
 
   const registerChild = useCallback(
@@ -171,7 +191,13 @@ export const ActionBar: React.FC<React.PropsWithChildren<ActionBarProps>> = prop
   const [menuItemIds, setMenuItemIds] = useState<Set<string>>(() => new Set())
 
   const navRef = useRef<HTMLDivElement>(null)
-  const listRef = useRef<HTMLDivElement>(null)
+  // measure gap after first render & whenever gap scale changes
+  useIsomorphicLayoutEffect(() => {
+    if (!listRef.current) return
+    const g = window.getComputedStyle(listRef.current).gap
+    const parsed = parseFloat(g)
+    if (!Number.isNaN(parsed)) setComputedGap(parsed)
+  }, [gap])
   const moreMenuRef = useRef<HTMLLIElement>(null)
   const moreMenuBtnRef = useRef<HTMLButtonElement>(null)
   const containerRef = React.useRef<HTMLUListElement>(null)
@@ -182,7 +208,7 @@ export const ActionBar: React.FC<React.PropsWithChildren<ActionBarProps>> = prop
     const hasActiveMenu = menuItemIds.size > 0
 
     if (navWidth > 0) {
-      const newMenuItemIds = getMenuItems(navWidth, moreMenuWidth, childRegistry, hasActiveMenu)
+      const newMenuItemIds = getMenuItems(navWidth, moreMenuWidth, childRegistry, hasActiveMenu, computedGap)
       if (newMenuItemIds) setMenuItemIds(newMenuItemIds)
     }
   }, navRef as RefObject<HTMLElement>)
@@ -230,9 +256,9 @@ export const ActionBar: React.FC<React.PropsWithChildren<ActionBarProps>> = prop
           ref={listRef}
           role="toolbar"
           className={styles.List}
-          style={{gap: `${ACTIONBAR_ITEM_GAP}px`}}
           aria-label={ariaLabel}
           aria-labelledby={ariaLabelledBy}
+          data-gap={gap}
         >
           {children}
           {menuItemIds.size > 0 && (