diff --git a/packages/compiler-sfc/__tests__/compileScript.spec.ts b/packages/compiler-sfc/__tests__/compileScript.spec.ts
index 08d404b9c16..068a050ca73 100644
--- a/packages/compiler-sfc/__tests__/compileScript.spec.ts
+++ b/packages/compiler-sfc/__tests__/compileScript.spec.ts
@@ -801,6 +801,7 @@ const emit = defineEmits(['a', 'b'])
         symbol: symbol
 
         union: string | number
+        unionWithUndefined: number | undefined
         literalUnion: 'foo' | 'bar'
         literalUnionNumber: 1 | 2 | 3 | 4 | 5
         literalUnionMixed: 'foo' | 1 | boolean
@@ -832,6 +833,9 @@ const emit = defineEmits(['a', 'b'])
       expect(content).toMatch(
         `union: { type: [String, Number], required: true }`
       )
+      expect(content).toMatch(
+        `unionWithUndefined: { type: Number, required: false }`
+      )
       expect(content).toMatch(`literalUnion: { type: String, required: true }`)
       expect(content).toMatch(
         `literalUnionNumber: { type: Number, required: true }`
diff --git a/packages/compiler-sfc/src/compileScript.ts b/packages/compiler-sfc/src/compileScript.ts
index 5a77e8a9463..6d8ea54d6dc 100644
--- a/packages/compiler-sfc/src/compileScript.ts
+++ b/packages/compiler-sfc/src/compileScript.ts
@@ -1756,9 +1756,16 @@ function extractRuntimeProps(
       } else if (m.typeAnnotation) {
         type = inferRuntimeType(m.typeAnnotation.typeAnnotation, declaredTypes)
       }
+
+      let undefinedIdx = type?.indexOf('undefined') ?? -1
+
+      if (undefinedIdx > -1) {
+        type?.splice(undefinedIdx, 1)
+      }
+
       props[m.key.name] = {
         key: m.key.name,
-        required: !m.optional,
+        required: !m.optional && undefinedIdx === -1,
         type: type || [`null`]
       }
     }
@@ -1847,6 +1854,9 @@ function inferRuntimeType(
     case 'TSSymbolKeyword':
       return ['Symbol']
 
+    case 'TSUndefinedKeyword':
+      return ['undefined']
+
     default:
       return [`null`] // no runtime check
   }