diff --git a/CHANGELOG.md b/CHANGELOG.md
index 084028ccb..34d5c1b9a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Remove deprecation warnings by using `Module#registerHooks` instead of `Module#register` on Node 26+ ([#20028](https://github.com/tailwindlabs/tailwindcss/pull/20028))
 - Canonicalization: don't crash when plugin utilities throw for unsupported values ([#20052](https://github.com/tailwindlabs/tailwindcss/pull/20052))
 - Allow `@apply` to be used with CSS mixins ([#19427](https://github.com/tailwindlabs/tailwindcss/pull/19427))
+- Ensure `not-*` correctly negates `@container` queries, including `style(…)` queries ([#20059](https://github.com/tailwindlabs/tailwindcss/pull/20059))
 
 ## [4.3.0] - 2026-05-08
 
diff --git a/packages/tailwindcss/src/variants.test.ts b/packages/tailwindcss/src/variants.test.ts
index ff6f530c8..305859d5b 100644
--- a/packages/tailwindcss/src/variants.test.ts
+++ b/packages/tailwindcss/src/variants.test.ts
@@ -1770,6 +1770,69 @@ test('not', async () => {
     "
   `)
 
+  // https://github.com/tailwindlabs/tailwindcss/issues/20058
+  expect(
+    await run(
+      ['not-has-a:flex', 'not-has-b:flex', 'not-has-c:flex', 'not-has-d:flex'],
+      css`
+        @custom-variant has-a {
+          @container style(--a) {
+            @slot;
+          }
+        }
+
+        /* Already negated case */
+        @custom-variant has-b {
+          @container not style(--b) {
+            @slot;
+          }
+        }
+
+        /* Named @container */
+        @custom-variant has-c {
+          @container foo style(--c) {
+            @slot;
+          }
+        }
+
+        /* Named @container, that's already negated case */
+        @custom-variant has-d {
+          @container bar not style(--d) {
+            @slot;
+          }
+        }
+
+        @tailwind utilities;
+      `,
+    ),
+  ).toMatchInlineSnapshot(`
+    "
+    @container not style(--a) {
+      .not-has-a\\:flex {
+        display: flex;
+      }
+    }
+
+    @container style(--b) {
+      .not-has-b\\:flex {
+        display: flex;
+      }
+    }
+
+    @container foo not style(--c) {
+      .not-has-c\\:flex {
+        display: flex;
+      }
+    }
+
+    @container bar style(--d) {
+      .not-has-d\\:flex {
+        display: flex;
+      }
+    }
+    "
+  `)
+
   expect(
     await run(
       [
diff --git a/packages/tailwindcss/src/variants.ts b/packages/tailwindcss/src/variants.ts
index 76ead2dc9..4d4637d8f 100644
--- a/packages/tailwindcss/src/variants.ts
+++ b/packages/tailwindcss/src/variants.ts
@@ -19,6 +19,7 @@ import { compareBreakpoints } from './utils/compare-breakpoints'
 import { DefaultMap } from './utils/default-map'
 import { isPositiveInteger } from './utils/infer-data-type'
 import { segment } from './utils/segment'
+import * as ValueParser from './value-parser'
 import { walk, WalkAction } from './walk'
 
 export const IS_VALID_VARIANT_NAME = /^@?[a-z0-9][a-zA-Z0-9_-]*(?<![_-])$/
@@ -375,35 +376,83 @@ export function createVariants(theme: Theme): Variants {
 
   function negateConditions(ruleName: string, conditions: string[]) {
     return conditions.map((condition) => {
-      condition = condition.trim()
+      switch (ruleName) {
+        case '@container': {
+          let ast = ValueParser.parse(condition.trim())
 
-      let parts = segment(condition, ' ')
+          // @container {query}
+          //            ^^^^^^^
+          // ast        0
+          if (ast.length >= 1 && ast[0].kind === 'function') {
+            return `not ${condition}`
+          }
 
-      // @media not {query}
-      // @supports not {query}
-      // @container not {query}
-      if (parts[0] === 'not') {
-        return parts.slice(1).join(' ')
-      }
+          // @container not   {query}
+          //            ^^^ ^ ^^^^^^^
+          // ast        0   1 2
+          else if (
+            ast.length >= 3 &&
+            ast[0].kind === 'word' &&
+            ast[0].value === 'not' &&
+            ast[2].kind === 'function'
+          ) {
+            // Drop the leading `not` (ast[0]) and separator (ast[1])
+            ast.splice(0, 2)
+
+            return ValueParser.toCss(ast)
+          }
+
+          // @container {name}   not   {query}
+          //            ^^^^^^ ^ ^^^ ^ ^^^^^^^
+          // ast        0      1 2   3 4
+          else if (
+            ast.length >= 5 &&
+            ast[0].kind === 'word' &&
+            ast[2].kind === 'word' &&
+            ast[2].value === 'not' &&
+            ast[4].kind === 'function'
+          ) {
+            // Drop the `not` (ast[2]) and separator (ast[3])
+            ast.splice(2, 2)
+
+            return ValueParser.toCss(ast)
+          }
+
+          // @container {name}   {query}
+          //            ^^^^^^ ^ ^^^^^^^
+          // ast        0      1 2
+          else if (
+            ast.length >= 3 &&
+            ast[0].kind === 'word' &&
+            ast[0].value !== 'not' &&
+            ast[2].kind === 'function'
+          ) {
+            // Inject a separator and a `not`, after the `name` (ast[0])
+            ast.splice(1, 0, { kind: 'separator', value: ' ' }, { kind: 'word', value: 'not' })
+
+            return ValueParser.toCss(ast)
+          }
+
+          // Fallback
+          else {
+            return `not ${condition}`
+          }
+        }
+
+        default: {
+          condition = condition.trim()
+
+          let parts = segment(condition, ' ')
+
+          // @media not {query}
+          // @supports not {query}
+          if (parts[0] === 'not') {
+            return parts.slice(1).join(' ')
+          }
 
-      if (ruleName === '@container') {
-        // @container {query}
-        if (parts[0][0] === '(') {
           return `not ${condition}`
         }
-
-        // @container {name} not {query}
-        else if (parts[1] === 'not') {
-          return `${parts[0]} ${parts.slice(2).join(' ')}`
-        }
-
-        // @container {name} {query}
-        else {
-          return `${parts[0]} not ${parts.slice(1).join(' ')}`
-        }
       }
-
-      return `not ${condition}`
     })
   }