diff --git a/.chronus/changes/validate-useauth-unique-2024-1-27-17-26-52.md b/.chronus/changes/validate-useauth-unique-2024-1-27-17-26-52.md
new file mode 100644
index 0000000000..c76ad570bf
--- /dev/null
+++ b/.chronus/changes/validate-useauth-unique-2024-1-27-17-26-52.md
@@ -0,0 +1,8 @@
+---
+# Change versionKind to one of: internal, fix, dependencies, feature, deprecation, breaking
+changeKind: feature
+packages:
+  - "@typespec/http"
+---
+
+Validate that only one `@useAuth` decorator is applied to a type.
diff --git a/packages/http/src/decorators.ts b/packages/http/src/decorators.ts
index 54e37b8892..758f843dc2 100644
--- a/packages/http/src/decorators.ts
+++ b/packages/http/src/decorators.ts
@@ -436,6 +436,7 @@ export function $useAuth(
   entity: Namespace | Interface | Operation,
   authConfig: Model | Union | Tuple
 ) {
+  validateDecoratorUniqueOnNode(context, entity, $useAuth);
   const [auth, diagnostics] = extractAuthentication(context.program, authConfig);
   if (diagnostics.length > 0) context.program.reportDiagnostics(diagnostics);
   if (auth !== undefined) {