diff --git a/CHANGELOG.md b/CHANGELOG.md
index 99b35a7d755e..3514751e54e1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Fixed
 
 - Substitute `@variant` inside legacy JS APIs ([#19263](https://github.com/tailwindlabs/tailwindcss/pull/19263))
+- Escape variant modifiers when used in selectors and at-rules ([#19269](https://github.com/tailwindlabs/tailwindcss/pull/19269))
 
 ### Added
 
diff --git a/packages/tailwindcss/src/variants.test.ts b/packages/tailwindcss/src/variants.test.ts
index a2540e698d7b..2fc3e5449eb4 100644
--- a/packages/tailwindcss/src/variants.test.ts
+++ b/packages/tailwindcss/src/variants.test.ts
@@ -586,11 +586,13 @@ test('group-*', async () => {
 
         'group-hover:group-focus:flex',
         'group-focus:group-hover:flex',
+
+        'group-hover/foo+bar:flex',
       ],
     ),
   ).toMatchInlineSnapshot(`
     "@media (hover: hover) {
-      .group-hover\\:flex:is(:where(.group):hover *) {
+      .group-hover\\:flex:is(:where(.group):hover *), .group-hover\\/foo\\+bar\\:flex:is(:where(.group\\/foo\\+bar):hover *) {
         display: flex;
       }
     }
@@ -677,11 +679,13 @@ test('peer-*', async () => {
         'peer-hocus:flex',
         'peer-hover:peer-focus:flex',
         'peer-focus:peer-hover:flex',
+
+        'peer-hover/foo+bar:flex',
       ],
     ),
   ).toMatchInlineSnapshot(`
     "@media (hover: hover) {
-      .peer-hover\\:flex:is(:where(.peer):hover ~ *) {
+      .peer-hover\\:flex:is(:where(.peer):hover ~ *), .peer-hover\\/foo\\+bar\\:flex:is(:where(.peer\\/foo\\+bar):hover ~ *) {
         display: flex;
       }
     }
@@ -2081,6 +2085,7 @@ test('container queries', async () => {
       [
         '@lg:flex',
         '@lg/name:flex',
+        '@lg/foo+bar:flex',
         '@[123px]:flex',
         '@[456px]/name:flex',
         '@foo-bar:flex',
@@ -2088,6 +2093,7 @@ test('container queries', async () => {
 
         '@min-lg:flex',
         '@min-lg/name:flex',
+        '@min-lg/foo+bar:flex',
         '@min-[123px]:flex',
         '@min-[456px]/name:flex',
         '@min-foo-bar:flex',
@@ -2095,6 +2101,7 @@ test('container queries', async () => {
 
         '@max-lg:flex',
         '@max-lg/name:flex',
+        '@max-lg/foo+bar:flex',
         '@max-[123px]:flex',
         '@max-[456px]/name:flex',
         '@max-foo-bar:flex',
@@ -2114,6 +2121,12 @@ test('container queries', async () => {
       }
     }
 
+    @container foo\\+bar not (min-width: 1024px) {
+      .\\@max-lg\\/foo\\+bar\\:flex {
+        display: flex;
+      }
+    }
+
     @container name not (min-width: 1024px) {
       .\\@max-lg\\/name\\:flex {
         display: flex;
@@ -2150,6 +2163,12 @@ test('container queries', async () => {
       }
     }
 
+    @container foo\\+bar (min-width: 1024px) {
+      .\\@lg\\/foo\\+bar\\:flex {
+        display: flex;
+      }
+    }
+
     @container name (min-width: 1024px) {
       .\\@lg\\/name\\:flex {
         display: flex;
@@ -2162,6 +2181,12 @@ test('container queries', async () => {
       }
     }
 
+    @container foo\\+bar (min-width: 1024px) {
+      .\\@min-lg\\/foo\\+bar\\:flex {
+        display: flex;
+      }
+    }
+
     @container name (min-width: 1024px) {
       .\\@min-lg\\/name\\:flex {
         display: flex;
diff --git a/packages/tailwindcss/src/variants.ts b/packages/tailwindcss/src/variants.ts
index 82a2b8592cfe..e7883bdfe2bf 100644
--- a/packages/tailwindcss/src/variants.ts
+++ b/packages/tailwindcss/src/variants.ts
@@ -17,6 +17,7 @@ import type { DesignSystem } from './design-system'
 import type { Theme } from './theme'
 import { compareBreakpoints } from './utils/compare-breakpoints'
 import { DefaultMap } from './utils/default-map'
+import { escape } from './utils/escape'
 import { isPositiveInteger } from './utils/infer-data-type'
 import { segment } from './utils/segment'
 import { walk, WalkAction } from './walk'
@@ -522,7 +523,7 @@ export function createVariants(theme: Theme): Variants {
     // Name the group by appending the modifier to `group` class itself if
     // present.
     let variantSelector = variant.modifier
-      ? `:where(.${theme.prefix ? `${theme.prefix}\\:` : ''}group\\/${variant.modifier.value})`
+      ? `:where(.${theme.prefix ? `${theme.prefix}\\:` : ''}group\\/${escape(variant.modifier.value)})`
       : `:where(.${theme.prefix ? `${theme.prefix}\\:` : ''}group)`
 
     let didApply = false
@@ -574,7 +575,7 @@ export function createVariants(theme: Theme): Variants {
     // Name the peer by appending the modifier to `peer` class itself if
     // present.
     let variantSelector = variant.modifier
-      ? `:where(.${theme.prefix ? `${theme.prefix}\\:` : ''}peer\\/${variant.modifier.value})`
+      ? `:where(.${theme.prefix ? `${theme.prefix}\\:` : ''}peer\\/${escape(variant.modifier.value)})`
       : `:where(.${theme.prefix ? `${theme.prefix}\\:` : ''}peer)`
 
     let didApply = false
@@ -1063,7 +1064,7 @@ export function createVariants(theme: Theme): Variants {
                 atRule(
                   '@container',
                   variant.modifier
-                    ? `${variant.modifier.value} (width < ${value})`
+                    ? `${escape(variant.modifier.value)} (width < ${value})`
                     : `(width < ${value})`,
                   ruleNode.nodes,
                 ),
@@ -1092,7 +1093,7 @@ export function createVariants(theme: Theme): Variants {
                 atRule(
                   '@container',
                   variant.modifier
-                    ? `${variant.modifier.value} (width >= ${value})`
+                    ? `${escape(variant.modifier.value)} (width >= ${value})`
                     : `(width >= ${value})`,
                   ruleNode.nodes,
                 ),
@@ -1110,7 +1111,7 @@ export function createVariants(theme: Theme): Variants {
                 atRule(
                   '@container',
                   variant.modifier
-                    ? `${variant.modifier.value} (width >= ${value})`
+                    ? `${escape(variant.modifier.value)} (width >= ${value})`
                     : `(width >= ${value})`,
                   ruleNode.nodes,
                 ),