diff --git a/packages/amplify-graphql-default-value-transformer/package.json b/packages/amplify-graphql-default-value-transformer/package.json
index 32bf38253d..9839b40476 100644
--- a/packages/amplify-graphql-default-value-transformer/package.json
+++ b/packages/amplify-graphql-default-value-transformer/package.json
@@ -75,7 +75,8 @@
       "src/**/*.ts"
     ],
     "coveragePathIgnorePatterns": [
-      "/__tests__/"
+      "/__tests__/",
+      "types.ts"
     ],
     "snapshotFormat": {
       "escapeString": true,
diff --git a/packages/amplify-graphql-default-value-transformer/src/graphql-default-value-transformer.ts b/packages/amplify-graphql-default-value-transformer/src/graphql-default-value-transformer.ts
index 41a0e8855b..01fd4b424f 100644
--- a/packages/amplify-graphql-default-value-transformer/src/graphql-default-value-transformer.ts
+++ b/packages/amplify-graphql-default-value-transformer/src/graphql-default-value-transformer.ts
@@ -20,6 +20,7 @@ import {
   FieldDefinitionNode,
   InterfaceTypeDefinitionNode,
   Kind,
+  ListValueNode,
   ObjectTypeDefinitionNode,
   StringValueNode,
   TypeNode,
@@ -82,11 +83,24 @@ const validateNotPrimaryKey = (field: FieldDefinitionNode): void => {
   }
 };
 
+const validateNotCompositeKeyMember = (config: DefaultValueDirectiveConfiguration): void => {
+  const objectDirectives = config.object.fields?.flatMap((f) => f.directives);
+  const primaryKeyDirective = objectDirectives?.find((dir) => dir?.name.value === 'primaryKey');
+  if (primaryKeyDirective) {
+    const sortKeyFields = primaryKeyDirective.arguments?.find((arg) => arg.name.value === 'sortKeyFields')?.value as ListValueNode;
+    const sortKeys = sortKeyFields?.values as StringValueNode[];
+    if (sortKeys?.some((sortKey) => sortKey.value === config.field.name.value)) {
+      throw new InvalidDirectiveError('The @default directive may not be applied to composite key member fields.');
+    }
+  }
+};
+
 const validate = (ctx: TransformerSchemaVisitStepContextProvider, config: DefaultValueDirectiveConfiguration): void => {
   validateModelDirective(config);
   validateFieldType(ctx, config.field.type);
   validateDirectiveArguments(config.directive);
   validateNotPrimaryKey(config.field);
+  validateNotCompositeKeyMember(config);
 
   // Validate the default values only for the DynamoDB datasource.
   // For SQL, the database determines and sets the default value. We will not validate the value in transformers.