diff --git a/packages/tailwindcss-language-server/src/language/css-server.ts b/packages/tailwindcss-language-server/src/language/css-server.ts
index a43910b22..73e967fcc 100644
--- a/packages/tailwindcss-language-server/src/language/css-server.ts
+++ b/packages/tailwindcss-language-server/src/language/css-server.ts
@@ -13,7 +13,7 @@ import {
   CompletionItemKind,
   Connection,
 } from 'vscode-languageserver/node'
-import { TextDocument } from 'vscode-languageserver-textdocument'
+import { Position, TextDocument } from 'vscode-languageserver-textdocument'
 import { Utils, URI } from 'vscode-uri'
 import { getLanguageModelCache } from './languageModelCache'
 import { Stylesheet } from 'vscode-css-languageservice'
@@ -121,6 +121,7 @@ export class CssServer {
     async function withDocumentAndSettings<T>(
       uri: string,
       callback: (result: {
+        original: TextDocument
         document: TextDocument
         settings: LanguageSettings | undefined
       }) => T | Promise<T>,
@@ -130,13 +131,64 @@ export class CssServer {
         return null
       }
       return await callback({
+        original: document,
         document: createVirtualCssDocument(document),
         settings: await getDocumentSettings(document),
       })
     }
 
+    function isInImportDirective(doc: TextDocument, pos: Position) {
+      let text = doc.getText({
+        start: { line: pos.line, character: 0 },
+        end: pos,
+      })
+
+      // Scan backwards to see if we're inside an `@import` directive
+      let foundImport = false
+      let foundDirective = false
+
+      for (let i = text.length - 1; i >= 0; i--) {
+        let char = text[i]
+        if (char === '\n') break
+
+        if (char === '(' && !foundDirective) {
+          if (text.startsWith(' source(', i - 7)) {
+            foundDirective = true
+          }
+
+          //
+          else if (text.startsWith(' theme(', i - 6)) {
+            foundDirective = true
+          }
+
+          //
+          else if (text.startsWith(' prefix(', i - 7)) {
+            foundDirective = true
+          }
+        }
+
+        //
+        else if (char === '@' && !foundImport) {
+          if (text.startsWith('@import ', i)) {
+            foundImport = true
+          }
+        }
+      }
+
+      return foundImport && foundDirective
+    }
+
     connection.onCompletion(async ({ textDocument, position }, _token) =>
-      withDocumentAndSettings(textDocument.uri, async ({ document, settings }) => {
+      withDocumentAndSettings(textDocument.uri, async ({ original, document, settings }) => {
+        // If we're inside source(…), prefix(…), or theme(…), don't show
+        // completions from the CSS language server
+        if (isInImportDirective(original, position)) {
+          return {
+            isIncomplete: false,
+            items: [],
+          }
+        }
+
         let result = await cssLanguageService.doComplete2(
           document,
           position,
diff --git a/packages/tailwindcss-language-server/tests/css/css-server.test.ts b/packages/tailwindcss-language-server/tests/css/css-server.test.ts
index e8970e08a..388e94af7 100644
--- a/packages/tailwindcss-language-server/tests/css/css-server.test.ts
+++ b/packages/tailwindcss-language-server/tests/css/css-server.test.ts
@@ -689,3 +689,49 @@ defineTest({
     expect(await doc.diagnostics()).toEqual([])
   },
 })
+
+defineTest({
+  name: 'completions are hidden inside @import source(…)/theme(…)/prefix(…) functions',
+  prepare: async ({ root }) => ({
+    client: await createClient({
+      server: 'css',
+      root,
+    }),
+  }),
+  handle: async ({ client }) => {
+    let doc = await client.open({
+      lang: 'tailwindcss',
+      name: 'file-1.css',
+      text: css`
+        @import './file.css' source(none);
+        @import './file.css' theme(inline);
+        @import './file.css' prefix(tw);
+        @import './file.css' source(none) theme(inline) prefix(tw);
+      `,
+    })
+
+    // @import './file.css' source(none)
+    //                             ^
+    // @import './file.css' theme(inline);
+    //                            ^
+    // @import './file.css' prefix(tw);
+    //                             ^
+    let completionsA = await doc.completions({ line: 0, character: 29 })
+    let completionsB = await doc.completions({ line: 1, character: 28 })
+    let completionsC = await doc.completions({ line: 2, character: 29 })
+
+    expect(completionsA).toEqual({ isIncomplete: false, items: [] })
+    expect(completionsB).toEqual({ isIncomplete: false, items: [] })
+    expect(completionsC).toEqual({ isIncomplete: false, items: [] })
+
+    // @import './file.css' source(none) theme(inline) prefix(tw);
+    //                             ^           ^              ^
+    let completionsD = await doc.completions({ line: 3, character: 29 })
+    let completionsE = await doc.completions({ line: 3, character: 41 })
+    let completionsF = await doc.completions({ line: 3, character: 56 })
+
+    expect(completionsD).toEqual({ isIncomplete: false, items: [] })
+    expect(completionsE).toEqual({ isIncomplete: false, items: [] })
+    expect(completionsF).toEqual({ isIncomplete: false, items: [] })
+  },
+})
diff --git a/packages/vscode-tailwindcss/CHANGELOG.md b/packages/vscode-tailwindcss/CHANGELOG.md
index 31a8ca66a..824781252 100644
--- a/packages/vscode-tailwindcss/CHANGELOG.md
+++ b/packages/vscode-tailwindcss/CHANGELOG.md
@@ -2,7 +2,7 @@
 
 ## Prerelease
 
-- Nothing yet!
+- Hide completions from CSS language server inside `@import "…" source(…)` ([#1091](https://github.com/tailwindlabs/tailwindcss-intellisense/pull/1091))
 
 # 0.14.12