diff --git a/.changeset/modern-chicken-happen.md b/.changeset/modern-chicken-happen.md
new file mode 100644
index 00000000000..d39feed1824
--- /dev/null
+++ b/.changeset/modern-chicken-happen.md
@@ -0,0 +1,6 @@
+---
+"@primer/react": major
+"@primer/styled-react": patch
+---
+
+chore: remove sx from deprecated Dialog
diff --git a/packages/react/src/DialogV1/Dialog.tsx b/packages/react/src/DialogV1/Dialog.tsx
index 3764f29d6de..da422694c88 100644
--- a/packages/react/src/DialogV1/Dialog.tsx
+++ b/packages/react/src/DialogV1/Dialog.tsx
@@ -1,13 +1,11 @@
 import React, {forwardRef, useRef, type HTMLAttributes} from 'react'
 import {IconButton} from '../Button'
 import useDialog from '../hooks/useDialog'
-import type {SxProp} from '../sx'
 import type {ComponentProps} from '../utils/types'
 import {useRefObjectAsForwardedRef} from '../hooks/useRefObjectAsForwardedRef'
 import {XIcon} from '@primer/octicons-react'
 import {clsx} from 'clsx'
 import classes from './Dialog.module.css'
-import {BoxWithFallback} from '../internal/components/BoxWithFallback'
 
 // Dialog v1
 const noop = () => null
@@ -15,19 +13,22 @@ const noop = () => null
 type StyledDialogBaseProps = {
   narrow?: boolean
   wide?: boolean
-} & SxProp
+  as?: React.ElementType
+}
 
-export type DialogHeaderProps = React.PropsWithChildren<HTMLAttributes<HTMLDivElement>> & SxProp
+export type DialogHeaderProps = React.PropsWithChildren<HTMLAttributes<HTMLDivElement>> & {
+  as?: React.ElementType
+}
 
-function DialogHeader({children, className, ...rest}: DialogHeaderProps) {
+function DialogHeader({children, className, as: Component = 'div', ...rest}: DialogHeaderProps) {
   if (React.Children.toArray(children).every(ch => typeof ch === 'string')) {
     children = <span className={classes.HeaderChild}>{children}</span>
   }
 
   return (
-    <BoxWithFallback as="div" {...rest} className={clsx(classes.Header, className)}>
+    <Component {...rest} className={clsx(classes.Header, className)}>
       {children}
-    </BoxWithFallback>
+    </Component>
   )
 }
 
@@ -36,11 +37,15 @@ type InternalDialogProps = {
   onDismiss?: () => void
   initialFocusRef?: React.RefObject<HTMLElement>
   returnFocusRef?: React.RefObject<HTMLElement>
+  as?: React.ElementType
 } & StyledDialogBaseProps &
   HTMLAttributes<HTMLDivElement>
 
 const Dialog = forwardRef<HTMLDivElement, InternalDialogProps>(
-  ({children, onDismiss = noop, isOpen, initialFocusRef, returnFocusRef, className, ...props}, forwardedRef) => {
+  (
+    {children, onDismiss = noop, isOpen, initialFocusRef, returnFocusRef, className, as: Component = 'div', ...props},
+    forwardedRef,
+  ) => {
     const overlayRef = useRef(null)
     const modalRef = useRef<HTMLDivElement>(null)
     useRefObjectAsForwardedRef(forwardedRef, modalRef)
@@ -65,9 +70,8 @@ const Dialog = forwardRef<HTMLDivElement, InternalDialogProps>(
 
     return isOpen ? (
       <>
-        <BoxWithFallback as="span" className={classes.Overlay} ref={overlayRef} />
-        <BoxWithFallback
-          as="div"
+        <span className={classes.Overlay} ref={overlayRef} />
+        <Component
           tabIndex={-1}
           ref={modalRef}
           role="dialog"
@@ -86,7 +90,7 @@ const Dialog = forwardRef<HTMLDivElement, InternalDialogProps>(
             className={classes.CloseIcon}
           />
           {children}
-        </BoxWithFallback>
+        </Component>
       </>
     ) : null
   },
diff --git a/packages/styled-react/src/__tests__/primer-react-deprecated.browser.test.tsx b/packages/styled-react/src/__tests__/primer-react-deprecated.browser.test.tsx
index 30c495916ce..4e7c24af6ab 100644
--- a/packages/styled-react/src/__tests__/primer-react-deprecated.browser.test.tsx
+++ b/packages/styled-react/src/__tests__/primer-react-deprecated.browser.test.tsx
@@ -5,13 +5,15 @@ import {Button} from '../index'
 
 describe('@primer/react/deprecated', () => {
   test('Dialog supports `sx` prop', () => {
-    render(<Dialog data-testid="component" isOpen sx={{background: 'red'}} />)
+    render(<Dialog as="button" data-testid="component" isOpen sx={{background: 'red'}} />)
     expect(window.getComputedStyle(screen.getByTestId('component')).backgroundColor).toBe('rgb(255, 0, 0)')
+    expect(screen.getByTestId('component').role).toBe('dialog')
   })
 
   test('Dialog.Header supports `sx` prop', () => {
-    render(<Dialog.Header data-testid="component" sx={{background: 'red'}} />)
+    render(<Dialog.Header as="button" data-testid="component" sx={{background: 'red'}} />)
     expect(window.getComputedStyle(screen.getByTestId('component')).backgroundColor).toBe('rgb(255, 0, 0)')
+    expect(screen.getByTestId('component').className.includes('Header')).toBe(true)
   })
 
   test('Octicon supports `sx` prop', () => {
diff --git a/packages/styled-react/src/components/DialogV1.tsx b/packages/styled-react/src/components/DialogV1.tsx
new file mode 100644
index 00000000000..a9907282fde
--- /dev/null
+++ b/packages/styled-react/src/components/DialogV1.tsx
@@ -0,0 +1,36 @@
+import {Dialog as PrimerDialog} from '@primer/react/deprecated'
+import type {
+  DialogProps as PrimerDialogProps,
+  DialogHeaderProps as PrimerDialogHeaderProps,
+} from '@primer/react/deprecated'
+import {Box} from './Box'
+import type {SxProp} from '../sx'
+import {forwardRef} from 'react'
+import type {ForwardRefComponent} from '../polymorphic'
+
+type DialogProps = PrimerDialogProps & SxProp
+
+const StyledDialog = forwardRef<HTMLDivElement, DialogProps>(function Dialog(props, ref) {
+  return <Box as={PrimerDialog} ref={ref} {...props} />
+})
+
+const DialogImpl = forwardRef(({as, ...props}: DialogProps, ref) => (
+  <StyledDialog {...props} {...(as ? {forwardedAs: as} : {})} ref={ref} />
+)) as ForwardRefComponent<'div', DialogProps>
+
+type DialogHeaderProps = PrimerDialogHeaderProps & SxProp
+
+const StyledDialogHeader = forwardRef<HTMLDivElement, DialogHeaderProps>(function DialogHeader(props, ref) {
+  return <Box as={PrimerDialog.Header} ref={ref} {...props} />
+})
+
+const DialogHeader = forwardRef(({as, ...props}: DialogHeaderProps, ref) => (
+  <StyledDialogHeader {...props} {...(as ? {forwardedAs: as} : {})} ref={ref} />
+)) as ForwardRefComponent<'div', DialogHeaderProps>
+
+const Dialog = Object.assign(DialogImpl, {
+  Header: DialogHeader,
+})
+
+export {Dialog}
+export type {DialogProps, DialogHeaderProps}
diff --git a/packages/styled-react/src/deprecated.tsx b/packages/styled-react/src/deprecated.tsx
index fb375d8b666..b5b2a030438 100644
--- a/packages/styled-react/src/deprecated.tsx
+++ b/packages/styled-react/src/deprecated.tsx
@@ -1,2 +1,3 @@
 export {TabNav, type TabNavProps, type TabNavLinkProps} from './components/TabNav'
-export {Dialog, Octicon, Tooltip, type TooltipProps} from '@primer/react/deprecated'
+export {Dialog, type DialogProps, type DialogHeaderProps} from './components/DialogV1'
+export {Octicon, Tooltip, type TooltipProps} from '@primer/react/deprecated'