diff --git a/.changeset/tall-cameras-unite.md b/.changeset/tall-cameras-unite.md
new file mode 100644
index 00000000000..f42cd2a8bad
--- /dev/null
+++ b/.changeset/tall-cameras-unite.md
@@ -0,0 +1,5 @@
+---
+"@primer/react": minor
+---
+
+Migrate TextInputAction & TextInputInnerVisualSlot to CSS Modules behind feature flag
diff --git a/packages/react/src/internal/components/TextInputInnerAction.module.css b/packages/react/src/internal/components/TextInputInnerAction.module.css
new file mode 100644
index 00000000000..f312c132f3e
--- /dev/null
+++ b/packages/react/src/internal/components/TextInputInnerAction.module.css
@@ -0,0 +1,31 @@
+.Invisible {
+  position: relative;
+  padding-top: var(--base-size-2);
+  padding-right: var(--base-size-4);
+  padding-bottom: var(--base-size-2);
+  padding-left: var(--base-size-4);
+  color: var(--fgColor-muted);
+  background-color: transparent;
+
+  &:hover,
+  &:focus {
+    color: var(--fgColor-default);
+  }
+
+  &[data-component='IconButton'] {
+    width: var(--inner-action-size);
+    height: var(--inner-action-size);
+  }
+
+  @media (pointer: coarse) {
+    ::after {
+      position: absolute;
+      top: 50%;
+      right: 0;
+      left: 0;
+      min-height: 44px;
+      content: '';
+      transform: translateY(-50%);
+    }
+  }
+}
diff --git a/packages/react/src/internal/components/TextInputInnerAction.tsx b/packages/react/src/internal/components/TextInputInnerAction.tsx
index 75fcb22349f..6a24a24f4c2 100644
--- a/packages/react/src/internal/components/TextInputInnerAction.tsx
+++ b/packages/react/src/internal/components/TextInputInnerAction.tsx
@@ -6,6 +6,11 @@ import {Tooltip} from '../../TooltipV2'
 import type {ButtonProps} from '../../Button'
 import type {BetterSystemStyleObject, SxProp} from '../../sx'
 import {merge} from '../../sx'
+import {clsx} from 'clsx'
+
+import styles from './TextInputInnerAction.module.css'
+import {useFeatureFlag} from '../../FeatureFlags'
+import {TEXT_INPUT_CSS_MODULES_FEATURE_FLAG} from './UnstyledTextInput'
 
 type TextInputActionProps = Omit<
   React.ButtonHTMLAttributes<HTMLButtonElement>,
@@ -89,15 +94,23 @@ const TextInputAction = forwardRef<HTMLButtonElement, TextInputActionProps>(
       children,
       icon,
       sx: sxProp,
+      className,
       variant = 'invisible',
       ...rest
     },
     forwardedRef,
   ) => {
-    const sx =
-      variant === 'invisible'
-        ? merge<BetterSystemStyleObject>(invisibleButtonStyleOverrides, sxProp || {})
-        : sxProp || {}
+    const enabled = useFeatureFlag(TEXT_INPUT_CSS_MODULES_FEATURE_FLAG)
+
+    const styleProps = enabled
+      ? {className: clsx(variant === 'invisible' && styles.Invisible, className), sx: sxProp || {}}
+      : {
+          className,
+          sx:
+            variant === 'invisible'
+              ? merge<BetterSystemStyleObject>(invisibleButtonStyleOverrides, sxProp || {})
+              : sxProp || {},
+        }
 
     if ((icon && !ariaLabel) || (!children && !ariaLabel)) {
       // eslint-disable-next-line no-console
@@ -122,13 +135,13 @@ const TextInputAction = forwardRef<HTMLButtonElement, TextInputActionProps>(
             type="button"
             icon={icon}
             size="small"
-            sx={sx}
+            {...styleProps}
             {...rest}
             ref={forwardedRef}
           />
         ) : (
           <ConditionalTooltip aria-label={ariaLabel}>
-            <Button variant={variant} type="button" sx={sx} {...rest} ref={forwardedRef}>
+            <Button variant={variant} type="button" {...styleProps} {...rest} ref={forwardedRef}>
               {children}
             </Button>
           </ConditionalTooltip>
diff --git a/packages/react/src/internal/components/TextInputInnerVisualSlot.module.css b/packages/react/src/internal/components/TextInputInnerVisualSlot.module.css
new file mode 100644
index 00000000000..acf4539155a
--- /dev/null
+++ b/packages/react/src/internal/components/TextInputInnerVisualSlot.module.css
@@ -0,0 +1,19 @@
+.Spinner {
+  position: absolute;
+  top: 0;
+  right: 0;
+  max-width: 100%;
+  height: 100%;
+}
+
+.SpinnerLeading {
+  left: 0;
+}
+
+.SpinnerHidden {
+  visibility: hidden;
+}
+
+.SpinnerVisible {
+  visibility: visible;
+}
diff --git a/packages/react/src/internal/components/TextInputInnerVisualSlot.tsx b/packages/react/src/internal/components/TextInputInnerVisualSlot.tsx
index 13e6342a6fc..44cd3758c76 100644
--- a/packages/react/src/internal/components/TextInputInnerVisualSlot.tsx
+++ b/packages/react/src/internal/components/TextInputInnerVisualSlot.tsx
@@ -1,8 +1,13 @@
 import React from 'react'
 import Box from '../../Box'
 import Spinner from '../../Spinner'
+import {clsx} from 'clsx'
 import type {TextInputNonPassthroughProps} from '../../TextInput'
 
+import styles from './TextInputInnerVisualSlot.module.css'
+import {useFeatureFlag} from '../../FeatureFlags'
+import {TEXT_INPUT_CSS_MODULES_FEATURE_FLAG} from './UnstyledTextInput'
+
 const TextInputInnerVisualSlot: React.FC<
   React.PropsWithChildren<{
     /** Whether the input is expected to ever show a loading indicator */
@@ -15,7 +20,9 @@ const TextInputInnerVisualSlot: React.FC<
     id?: string
   }>
 > = ({children, hasLoadingIndicator, showLoadingIndicator, visualPosition, id}) => {
-  if ((!children && !hasLoadingIndicator) || (visualPosition === 'leading' && !children && !showLoadingIndicator)) {
+  const enabled = useFeatureFlag(TEXT_INPUT_CSS_MODULES_FEATURE_FLAG)
+  const isLeading = visualPosition === 'leading'
+  if ((!children && !hasLoadingIndicator) || (isLeading && !children && !showLoadingIndicator)) {
     return null
   }
 
@@ -27,26 +34,40 @@ const TextInputInnerVisualSlot: React.FC<
     )
   }
 
+  const boxStyleProps = enabled
+    ? {className: clsx(showLoadingIndicator ? styles.SpinnerHidden : styles.SpinnerVisible)}
+    : {
+        sx: {
+          visibility: showLoadingIndicator ? 'hidden' : 'visible',
+        },
+      }
+
+  const spinnerStyleProps = enabled
+    ? {
+        className: clsx(
+          showLoadingIndicator ? styles.SpinnerVisible : styles.SpinnerHidden,
+          children && styles.Spinner,
+          children && isLeading && styles.SpinnerLeading,
+        ),
+      }
+    : {
+        sx: children
+          ? {
+              position: 'absolute',
+              top: 0,
+              height: '100%',
+              maxWidth: '100%',
+              visibility: showLoadingIndicator ? 'visible' : 'hidden',
+              ...(isLeading ? {left: 0} : {right: 0}),
+            }
+          : {visibility: showLoadingIndicator ? 'visible' : 'hidden'},
+      }
+
   return (
     <span className="TextInput-icon">
       <Box display="flex" position="relative" id={id}>
-        {children && <Box sx={{visibility: showLoadingIndicator ? 'hidden' : 'visible'}}>{children}</Box>}
-        <Spinner
-          srText={null}
-          sx={
-            children
-              ? {
-                  position: 'absolute',
-                  top: 0,
-                  height: '100%',
-                  maxWidth: '100%',
-                  visibility: showLoadingIndicator ? 'visible' : 'hidden',
-                  ...(visualPosition === 'leading' ? {left: 0} : {right: 0}),
-                }
-              : {visibility: showLoadingIndicator ? 'visible' : 'hidden'}
-          }
-          size={children ? undefined : 'small'}
-        />
+        {children && <Box {...boxStyleProps}>{children}</Box>}
+        <Spinner srText={null} {...spinnerStyleProps} size={children ? undefined : 'small'} />
       </Box>
     </span>
   )