diff --git a/CHANGELOG.md b/CHANGELOG.md
index 06d27203950a..23e50613bf2c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- _Experimental_: Add `user-valid` and `user-invalid` variants ([#12370](https://github.com/tailwindlabs/tailwindcss/pull/12370))
+
 ### Fixed
 
 - Export `tailwindcss/lib/util/flattenColorPalette.js` for backward compatibility ([#16411](https://github.com/tailwindlabs/tailwindcss/pull/16411))
diff --git a/packages/@tailwindcss-browser/tsup.config.ts b/packages/@tailwindcss-browser/tsup.config.ts
index 5a6d78273e65..bb0ddc39cde4 100644
--- a/packages/@tailwindcss-browser/tsup.config.ts
+++ b/packages/@tailwindcss-browser/tsup.config.ts
@@ -11,5 +11,6 @@ export default defineConfig({
   },
   define: {
     'process.env.NODE_ENV': '"production"',
+    'process.env.FEATURES_ENV': '"stable"',
   },
 })
diff --git a/packages/tailwindcss/src/__snapshots__/intellisense.test.ts.snap b/packages/tailwindcss/src/__snapshots__/intellisense.test.ts.snap
index 62c5f49a4a51..18384759c727 100644
--- a/packages/tailwindcss/src/__snapshots__/intellisense.test.ts.snap
+++ b/packages/tailwindcss/src/__snapshots__/intellisense.test.ts.snap
@@ -8405,6 +8405,8 @@ exports[`getVariants 1`] = `
       "required",
       "valid",
       "invalid",
+      "user-valid",
+      "user-invalid",
       "in-range",
       "out-of-range",
       "read-only",
@@ -8474,6 +8476,8 @@ exports[`getVariants 1`] = `
       "required",
       "valid",
       "invalid",
+      "user-valid",
+      "user-invalid",
       "in-range",
       "out-of-range",
       "read-only",
@@ -8527,6 +8531,8 @@ exports[`getVariants 1`] = `
       "required",
       "valid",
       "invalid",
+      "user-valid",
+      "user-invalid",
       "in-range",
       "out-of-range",
       "read-only",
@@ -8754,6 +8760,20 @@ exports[`getVariants 1`] = `
     "selectors": [Function],
     "values": [],
   },
+  {
+    "hasDash": true,
+    "isArbitrary": false,
+    "name": "user-valid",
+    "selectors": [Function],
+    "values": [],
+  },
+  {
+    "hasDash": true,
+    "isArbitrary": false,
+    "name": "user-invalid",
+    "selectors": [Function],
+    "values": [],
+  },
   {
     "hasDash": true,
     "isArbitrary": false,
@@ -8867,6 +8887,8 @@ exports[`getVariants 1`] = `
       "required",
       "valid",
       "invalid",
+      "user-valid",
+      "user-invalid",
       "in-range",
       "out-of-range",
       "read-only",
@@ -8920,6 +8942,8 @@ exports[`getVariants 1`] = `
       "required",
       "valid",
       "invalid",
+      "user-valid",
+      "user-invalid",
       "in-range",
       "out-of-range",
       "read-only",
diff --git a/packages/tailwindcss/src/feature-flags.ts b/packages/tailwindcss/src/feature-flags.ts
index b24550429193..e6db9b7a6261 100644
--- a/packages/tailwindcss/src/feature-flags.ts
+++ b/packages/tailwindcss/src/feature-flags.ts
@@ -1 +1,3 @@
 export const enableRemoveUnusedThemeVariables = false
+
+export const enableUserValid = process.env.FEATURES_ENV !== 'stable'
diff --git a/packages/tailwindcss/src/variants.test.ts b/packages/tailwindcss/src/variants.test.ts
index be374dbd9196..554be3c4d1b6 100644
--- a/packages/tailwindcss/src/variants.test.ts
+++ b/packages/tailwindcss/src/variants.test.ts
@@ -325,6 +325,34 @@ test('invalid', async () => {
   expect(await run(['invalid/foo:flex'])).toEqual('')
 })
 
+test('user-valid', async () => {
+  expect(await run(['user-valid:flex', 'group-user-valid:flex', 'peer-user-valid:flex']))
+    .toMatchInlineSnapshot(`
+      ".group-user-valid\\:flex:is(:where(.group):user-valid *), .peer-user-valid\\:flex:is(:where(.peer):user-valid ~ *) {
+        display: flex;
+      }
+
+      .user-valid\\:flex:user-valid {
+        display: flex;
+      }"
+    `)
+  expect(await run(['user-valid/foo:flex'])).toEqual('')
+})
+
+test('user-invalid', async () => {
+  expect(await run(['user-invalid:flex', 'group-user-invalid:flex', 'peer-user-invalid:flex']))
+    .toMatchInlineSnapshot(`
+      ".group-user-invalid\\:flex:is(:where(.group):user-invalid *), .peer-user-invalid\\:flex:is(:where(.peer):user-invalid ~ *) {
+        display: flex;
+      }
+
+      .user-invalid\\:flex:user-invalid {
+        display: flex;
+      }"
+    `)
+  expect(await run(['invalid/foo:flex'])).toEqual('')
+})
+
 test('in-range', async () => {
   expect(await run(['in-range:flex', 'group-in-range:flex', 'peer-in-range:flex']))
     .toMatchInlineSnapshot(`
diff --git a/packages/tailwindcss/src/variants.ts b/packages/tailwindcss/src/variants.ts
index 20f84c867453..ea1de7c8acb6 100644
--- a/packages/tailwindcss/src/variants.ts
+++ b/packages/tailwindcss/src/variants.ts
@@ -12,6 +12,7 @@ import {
   type StyleRule,
 } from './ast'
 import { type Variant } from './candidate'
+import { enableUserValid } from './feature-flags'
 import type { Theme } from './theme'
 import { compareBreakpoints } from './utils/compare-breakpoints'
 import { DefaultMap } from './utils/default-map'
@@ -692,6 +693,10 @@ export function createVariants(theme: Theme): Variants {
   staticVariant('required', ['&:required'])
   staticVariant('valid', ['&:valid'])
   staticVariant('invalid', ['&:invalid'])
+  if (enableUserValid) {
+    staticVariant('user-valid', ['&:user-valid'])
+    staticVariant('user-invalid', ['&:user-invalid'])
+  }
   staticVariant('in-range', ['&:in-range'])
   staticVariant('out-of-range', ['&:out-of-range'])
   staticVariant('read-only', ['&:read-only'])