diff --git a/packages/compiler-sfc/__tests__/parse.spec.ts b/packages/compiler-sfc/__tests__/parse.spec.ts
index 5f1db5e2499..767dc8fcef9 100644
--- a/packages/compiler-sfc/__tests__/parse.spec.ts
+++ b/packages/compiler-sfc/__tests__/parse.spec.ts
@@ -320,4 +320,60 @@ h1 { color: red }
       )
     })
   })
+
+  describe('default script lang', () => {
+    test('default lang for script', () => {
+      const { descriptor, errors } = parse(
+        `<script>console.log(0x0f)</script>`,
+        {
+          defaultScriptLang: 'ts'
+        }
+      )
+      expect(errors.length).toBe(0)
+      expect(descriptor.script?.lang).toBe('ts')
+    })
+
+    test('default lang for script setup', () => {
+      const { descriptor, errors } = parse(
+        `<script setup>console.log(0x03)</script>`,
+        {
+          defaultScriptLang: 'ts'
+        }
+      )
+      expect(errors.length).toBe(0)
+      expect(descriptor.scriptSetup?.lang).toBe('ts')
+    })
+
+    test('default lang for script & script setup', () => {
+      const { descriptor, errors } = parse(
+        `
+        <script>console.log(0x06)</script>
+        <script setup>console.log(0x07)</script>
+        `,
+        {
+          defaultScriptLang: 'ts'
+        }
+      )
+      expect(errors.length).toBe(0)
+      expect(descriptor.script?.lang).toBe('ts')
+      expect(descriptor.scriptSetup?.lang).toBe('ts')
+    })
+
+    // This only tests if the "source to sfc" cache has "defaultScriptLang" as part of the cache key.
+    test('source cache key', () => {
+      // The same SFC as previous test
+      const { descriptor, errors } = parse(
+        `
+        <script>console.log(0x06)</script>
+        <script setup>console.log(0x07)</script>
+        `,
+        {
+          defaultScriptLang: 'tsx'
+        }
+      )
+      expect(errors.length).toBe(0)
+      expect(descriptor.script?.lang).toBe('tsx')
+      expect(descriptor.scriptSetup?.lang).toBe('tsx')
+    })
+  })
 })
diff --git a/packages/compiler-sfc/src/parse.ts b/packages/compiler-sfc/src/parse.ts
index 79065fc667e..c4bde57b39f 100644
--- a/packages/compiler-sfc/src/parse.ts
+++ b/packages/compiler-sfc/src/parse.ts
@@ -22,6 +22,7 @@ export interface SFCParseOptions {
   pad?: boolean | 'line' | 'space'
   ignoreEmpty?: boolean
   compiler?: TemplateCompiler
+  defaultScriptLang?: string
 }
 
 export interface SFCBlock {
@@ -95,11 +96,18 @@ export function parse(
     sourceRoot = '',
     pad = false,
     ignoreEmpty = true,
-    compiler = CompilerDOM
+    compiler = CompilerDOM,
+    defaultScriptLang
   }: SFCParseOptions = {}
 ): SFCParseResult {
   const sourceKey =
-    source + sourceMap + filename + sourceRoot + pad + compiler.parse
+    source +
+    sourceMap +
+    filename +
+    sourceRoot +
+    pad +
+    compiler.parse +
+    (defaultScriptLang ? '@' + defaultScriptLang : '')
   const cache = sourceToSFC.get(sourceKey)
   if (cache) {
     return cache
@@ -191,10 +199,12 @@ export function parse(
         const scriptBlock = createBlock(node, source, pad) as SFCScriptBlock
         const isSetup = !!scriptBlock.attrs.setup
         if (isSetup && !descriptor.scriptSetup) {
+          if (!scriptBlock.lang) scriptBlock.lang = defaultScriptLang
           descriptor.scriptSetup = scriptBlock
           break
         }
         if (!isSetup && !descriptor.script) {
+          if (!scriptBlock.lang) scriptBlock.lang = defaultScriptLang
           descriptor.script = scriptBlock
           break
         }