diff --git a/.changeset/silent-cherries-behave.md b/.changeset/silent-cherries-behave.md
new file mode 100644
index 00000000000..ee09a911a13
--- /dev/null
+++ b/.changeset/silent-cherries-behave.md
@@ -0,0 +1,5 @@
+---
+"@primer/react": minor
+---
+
+Migrate 'InlineMessage' component to use CSS modules
diff --git a/.playwright/snapshots/components/InlineMessage.test.ts-snapshots/InlineMessage-Dev-Default-dark-colorblind-linux.png b/.playwright/snapshots/components/InlineMessage.test.ts-snapshots/InlineMessage-Dev-Default-dark-colorblind-linux.png
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diff --git a/.playwright/snapshots/components/InlineMessage.test.ts-snapshots/InlineMessage-Dev-Default-light-colorblind-linux.png b/.playwright/snapshots/components/InlineMessage.test.ts-snapshots/InlineMessage-Dev-Default-light-colorblind-linux.png
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diff --git a/.playwright/snapshots/components/InlineMessage.test.ts-snapshots/InlineMessage-Dev-Default-light-linux.png b/.playwright/snapshots/components/InlineMessage.test.ts-snapshots/InlineMessage-Dev-Default-light-linux.png
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diff --git a/.playwright/snapshots/components/InlineMessage.test.ts-snapshots/InlineMessage-Dev-Default-light-tritanopia-linux.png b/.playwright/snapshots/components/InlineMessage.test.ts-snapshots/InlineMessage-Dev-Default-light-tritanopia-linux.png
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diff --git a/e2e/components/InlineMessage.test.ts b/e2e/components/InlineMessage.test.ts
index cb595a96201..81814c82a20 100644
--- a/e2e/components/InlineMessage.test.ts
+++ b/e2e/components/InlineMessage.test.ts
@@ -12,6 +12,10 @@ const stories = [
     title: 'Multiline',
     id: 'experimental-components-inlinemessage-features--multiline',
   },
+  {
+    title: 'Dev Default',
+    id: 'experimental-components-inlinemessage-dev--dev-default',
+  },
 ]
 
 const scenarios = matrix({
diff --git a/packages/react/src/InlineMessage/InlineMessage.dev.stories.tsx b/packages/react/src/InlineMessage/InlineMessage.dev.stories.tsx
new file mode 100644
index 00000000000..69f87029b3a
--- /dev/null
+++ b/packages/react/src/InlineMessage/InlineMessage.dev.stories.tsx
@@ -0,0 +1,18 @@
+import type {Meta} from '@storybook/react'
+import React from 'react'
+import {InlineMessage} from '.'
+
+const meta = {
+  title: 'Experimental/Components/InlineMessage/Dev',
+  component: InlineMessage,
+} satisfies Meta<typeof InlineMessage>
+
+export default meta
+
+export const DevDefault = () => {
+  return (
+    <InlineMessage variant="unavailable" sx={{border: '1px solid red'}}>
+      An example inline message
+    </InlineMessage>
+  )
+}
diff --git a/packages/react/src/InlineMessage/InlineMessage.module.css b/packages/react/src/InlineMessage/InlineMessage.module.css
new file mode 100644
index 00000000000..0ddbea7498b
--- /dev/null
+++ b/packages/react/src/InlineMessage/InlineMessage.module.css
@@ -0,0 +1,42 @@
+.InlineMessage {
+  display: grid;
+  /* stylelint-disable-next-line primer/typography */
+  font-size: var(--inline-message-fontSize);
+  /* stylelint-disable-next-line primer/typography */
+  line-height: var(--inline-message-lineHeight);
+  /* stylelint-disable-next-line primer/colors */
+  color: var(--inline-message-fgColor);
+  column-gap: 0.5rem;
+  grid-template-columns: auto 1fr;
+  align-items: start;
+
+  &[data-size='small'] {
+    --inline-message-fontSize: var(--text-body-size-small);
+    --inline-message-lineHeight: var(--text-body-lineHeight-small, 1.6666);
+  }
+
+  &[data-size='medium'] {
+    --inline-message-fontSize: var(--text-body-size-medium);
+    --inline-message-lineHeight: var(--text-body-lineHeight-medium, 1.4285);
+  }
+
+  &[data-variant='warning'] {
+    --inline-message-fgColor: var(--fgColor-attention);
+  }
+
+  &[data-variant='critical'] {
+    --inline-message-fgColor: var(--fgColor-danger);
+  }
+
+  &[data-variant='success'] {
+    --inline-message-fgColor: var(--fgColor-success);
+  }
+
+  &[data-variant='unavailable'] {
+    --inline-message-fgColor: var(--fgColor-muted);
+  }
+}
+
+.InlineMessageIcon {
+  min-height: calc(var(--inline-message-lineHeight) * var(--inline-message-fontSize));
+}
diff --git a/packages/react/src/InlineMessage/InlineMessage.tsx b/packages/react/src/InlineMessage/InlineMessage.tsx
index 55f2296a6fd..173c9502f1b 100644
--- a/packages/react/src/InlineMessage/InlineMessage.tsx
+++ b/packages/react/src/InlineMessage/InlineMessage.tsx
@@ -1,80 +1,105 @@
 import {AlertFillIcon, AlertIcon, CheckCircleFillIcon, CheckCircleIcon} from '@primer/octicons-react'
+import {clsx} from 'clsx'
 import React from 'react'
 import styled from 'styled-components'
 import {get} from '../constants'
-
+import {toggleStyledComponent} from '../internal/utils/toggleStyledComponent'
+import {useFeatureFlag} from '../FeatureFlags'
+import classes from './InlineMessage.module.css'
+import type {SxProp} from '../sx'
 type MessageVariant = 'critical' | 'success' | 'unavailable' | 'warning'
 
-export type InlineMessageProps = React.ComponentPropsWithoutRef<'div'> & {
-  /**
-   * Specify the size of the InlineMessage
-   */
-  size?: 'small' | 'medium'
+const CSS_MODULES_FEATURE_FLAG = 'primer_react_css_modules_team'
 
-  /**
-   * Specify the type of the InlineMessage
-   */
-  variant: MessageVariant
-}
+export type InlineMessageProps = React.ComponentPropsWithoutRef<'div'> &
+  SxProp & {
+    /**
+     * Specify the size of the InlineMessage
+     */
+    size?: 'small' | 'medium'
 
-const StyledMessage = styled.div`
-  display: grid;
-  column-gap: 0.5rem;
-  grid-template-columns: auto 1fr;
-  align-items: start;
-  color: var(--inline-message-fgColor, ${get('colors.fg.muted')});
-  line-height: var(--inline-message-lineHeight);
-  font-size: var(--inline-message-fontSize, ${get('fontSizes.1')});
-
-  &[data-size='small'] {
-    --inline-message-fontSize: var(--text-body-size-small, ${get('fontSizes.0')});
-    --inline-message-lineHeight: var(--text-body-lineHeight-small, 1.6666);
+    /**
+     * Specify the type of the InlineMessage
+     */
+    variant: MessageVariant
   }
 
-  &[data-size='medium'] {
-    --inline-message-fontSize: var(--text-body-size-medium, ${get('fontSizes.1')});
-    --inline-message-lineHeight: var(--text-body-lineHeight-medium, 1.4285);
-  }
+const StyledMessage = toggleStyledComponent(
+  CSS_MODULES_FEATURE_FLAG,
+  'div',
+  styled.div`
+    display: grid;
+    column-gap: 0.5rem;
+    grid-template-columns: auto 1fr;
+    align-items: start;
+    color: var(--inline-message-fgColor, ${get('colors.fg.muted')});
+    line-height: var(--inline-message-lineHeight);
+    font-size: var(--inline-message-fontSize, ${get('fontSizes.1')});
 
-  &[data-variant='warning'] {
-    --inline-message-fgColor: ${get('colors.attention.fg')};
-  }
+    &[data-size='small'] {
+      --inline-message-fontSize: var(--text-body-size-small, ${get('fontSizes.0')});
+      --inline-message-lineHeight: var(--text-body-lineHeight-small, 1.6666);
+    }
 
-  &[data-variant='critical'] {
-    --inline-message-fgColor: ${get('colors.danger.fg')};
-  }
+    &[data-size='medium'] {
+      --inline-message-fontSize: var(--text-body-size-medium, ${get('fontSizes.1')});
+      --inline-message-lineHeight: var(--text-body-lineHeight-medium, 1.4285);
+    }
 
-  &[data-variant='success'] {
-    --inline-message-fgColor: ${get('colors.success.fg')};
-  }
+    &[data-variant='warning'] {
+      --inline-message-fgColor: ${get('colors.attention.fg')};
+    }
 
-  &[data-variant='unavailable'] {
-    --inline-message-fgColor: ${get('colors.fg.muted')};
-  }
+    &[data-variant='critical'] {
+      --inline-message-fgColor: ${get('colors.danger.fg')};
+    }
+
+    &[data-variant='success'] {
+      --inline-message-fgColor: ${get('colors.success.fg')};
+    }
+
+    &[data-variant='unavailable'] {
+      --inline-message-fgColor: ${get('colors.fg.muted')};
+    }
 
-  & .InlineMessageIcon {
-    min-height: calc(var(--inline-message-lineHeight) * var(--inline-message-fontSize));
+    & .InlineMessageIcon {
+      min-height: calc(var(--inline-message-lineHeight) * var(--inline-message-fontSize));
+    }
+  `,
+)
+
+const variantToIcon = (enabled: boolean, variant: MessageVariant): React.ReactNode => {
+  const icons = {
+    warning: <AlertIcon className={enabled ? classes.InlineMessageIcon : 'InlineMessageIcon'} />,
+    critical: <AlertIcon className={enabled ? classes.InlineMessageIcon : 'InlineMessageIcon'} />,
+    success: <CheckCircleIcon className={enabled ? classes.InlineMessageIcon : 'InlineMessageIcon'} />,
+    unavailable: <AlertIcon className={enabled ? classes.InlineMessageIcon : 'InlineMessageIcon'} />,
   }
-`
 
-const variantToIcon: Record<MessageVariant, React.ReactNode> = {
-  warning: <AlertIcon className="InlineMessageIcon" />,
-  critical: <AlertIcon className="InlineMessageIcon" />,
-  success: <CheckCircleIcon className="InlineMessageIcon" />,
-  unavailable: <AlertIcon className="InlineMessageIcon" />,
+  return icons[variant]
 }
 
-const variantToSmallIcon: Record<MessageVariant, React.ReactNode> = {
-  warning: <AlertFillIcon className="InlineMessageIcon" size={12} />,
-  critical: <AlertFillIcon className="InlineMessageIcon" size={12} />,
-  success: <CheckCircleFillIcon className="InlineMessageIcon" size={12} />,
-  unavailable: <AlertFillIcon className="InlineMessageIcon" size={12} />,
+const variantToSmallIcon = (enabled: boolean, variant: MessageVariant): React.ReactNode => {
+  const icons = {
+    warning: <AlertFillIcon className={classes.InlineMessageIcon} size={12} />,
+    critical: <AlertFillIcon className={classes.InlineMessageIcon} size={12} />,
+    success: <CheckCircleFillIcon className={classes.InlineMessageIcon} size={12} />,
+    unavailable: <AlertFillIcon className={classes.InlineMessageIcon} size={12} />,
+  }
+  return icons[variant]
 }
 
-export function InlineMessage({children, size = 'medium', variant, ...rest}: InlineMessageProps) {
-  const icon = size === 'small' ? variantToSmallIcon[variant] : variantToIcon[variant]
+export function InlineMessage({children, className, size = 'medium', variant, ...rest}: InlineMessageProps) {
+  const enabled = useFeatureFlag(CSS_MODULES_FEATURE_FLAG)
+
+  const icon = size === 'small' ? variantToSmallIcon(enabled, variant) : variantToIcon(enabled, variant)
   return (
-    <StyledMessage {...rest} data-size={size} data-variant={variant}>
+    <StyledMessage
+      className={clsx(className, enabled && classes.InlineMessage)}
+      {...rest}
+      data-size={size}
+      data-variant={variant}
+    >
       {icon}
       {children}
     </StyledMessage>