diff --git a/esphome/components/api/api.proto b/esphome/components/api/api.proto
index 34864c5ce8..c7d8fb28f0 100644
--- a/esphome/components/api/api.proto
+++ b/esphome/components/api/api.proto
@@ -866,7 +866,7 @@ message ListEntitiesServicesResponse {
 
   string name = 1;
   fixed32 key = 2;
-  repeated ListEntitiesServicesArgument args = 3;
+  repeated ListEntitiesServicesArgument args = 3 [(fixed_vector) = true];
 }
 message ExecuteServiceArgument {
   option (ifdef) = "USE_API_SERVICES";
diff --git a/esphome/components/api/api_pb2.h b/esphome/components/api/api_pb2.h
index 7d6b31ca3c..20866850a9 100644
--- a/esphome/components/api/api_pb2.h
+++ b/esphome/components/api/api_pb2.h
@@ -1263,7 +1263,7 @@ class ListEntitiesServicesResponse final : public ProtoMessage {
   StringRef name_ref_{};
   void set_name(const StringRef &ref) { this->name_ref_ = ref; }
   uint32_t key{0};
-  std::vector<ListEntitiesServicesArgument> args{};
+  FixedVector<ListEntitiesServicesArgument> args{};
   void encode(ProtoWriteBuffer buffer) const override;
   void calculate_size(ProtoSize &size) const override;
 #ifdef HAS_PROTO_MESSAGE_DUMP
diff --git a/esphome/components/api/user_services.h b/esphome/components/api/user_services.h
index 3996c921a9..29843a2f78 100644
--- a/esphome/components/api/user_services.h
+++ b/esphome/components/api/user_services.h
@@ -35,9 +35,9 @@ template<typename... Ts> class UserServiceBase : public UserServiceDescriptor {
     msg.set_name(StringRef(this->name_));
     msg.key = this->key_;
     std::array<enums::ServiceArgType, sizeof...(Ts)> arg_types = {to_service_arg_type<Ts>()...};
+    msg.args.init(sizeof...(Ts));
     for (size_t i = 0; i < sizeof...(Ts); i++) {
-      msg.args.emplace_back();
-      auto &arg = msg.args.back();
+      auto &arg = msg.args.emplace_back();
       arg.type = arg_types[i];
       arg.set_name(StringRef(this->arg_names_[i]));
     }