diff --git a/esphome/components/api/api.proto b/esphome/components/api/api.proto
index c7d8fb28f0..f7c51b8e97 100644
--- a/esphome/components/api/api.proto
+++ b/esphome/components/api/api.proto
@@ -876,10 +876,10 @@ message ExecuteServiceArgument {
   string string_ = 4;
   // ESPHome 1.14 (api v1.3) make int a signed value
   sint32 int_ = 5;
-  repeated bool bool_array = 6 [packed=false];
-  repeated sint32 int_array = 7 [packed=false];
-  repeated float float_array = 8 [packed=false];
-  repeated string string_array = 9;
+  repeated bool bool_array = 6 [packed=false, (fixed_vector) = true];
+  repeated sint32 int_array = 7 [packed=false, (fixed_vector) = true];
+  repeated float float_array = 8 [packed=false, (fixed_vector) = true];
+  repeated string string_array = 9 [(fixed_vector) = true];
 }
 message ExecuteServiceRequest {
   option (id) = 42;
@@ -888,7 +888,7 @@ message ExecuteServiceRequest {
   option (ifdef) = "USE_API_SERVICES";
 
   fixed32 key = 1;
-  repeated ExecuteServiceArgument args = 2;
+  repeated ExecuteServiceArgument args = 2 [(fixed_vector) = true];
 }
 
 // ==================== CAMERA ====================
diff --git a/esphome/components/api/api_pb2.cpp b/esphome/components/api/api_pb2.cpp
index 70bcf082a6..12b0bf6c98 100644
--- a/esphome/components/api/api_pb2.cpp
+++ b/esphome/components/api/api_pb2.cpp
@@ -1064,6 +1064,17 @@ bool ExecuteServiceArgument::decode_32bit(uint32_t field_id, Proto32Bit value) {
   }
   return true;
 }
+void ExecuteServiceArgument::decode(const uint8_t *buffer, size_t length) {
+  uint32_t count_bool_array = ProtoDecodableMessage::count_repeated_field(buffer, length, 6);
+  this->bool_array.init(count_bool_array);
+  uint32_t count_int_array = ProtoDecodableMessage::count_repeated_field(buffer, length, 7);
+  this->int_array.init(count_int_array);
+  uint32_t count_float_array = ProtoDecodableMessage::count_repeated_field(buffer, length, 8);
+  this->float_array.init(count_float_array);
+  uint32_t count_string_array = ProtoDecodableMessage::count_repeated_field(buffer, length, 9);
+  this->string_array.init(count_string_array);
+  ProtoDecodableMessage::decode(buffer, length);
+}
 bool ExecuteServiceRequest::decode_length(uint32_t field_id, ProtoLengthDelimited value) {
   switch (field_id) {
     case 2:
@@ -1085,6 +1096,11 @@ bool ExecuteServiceRequest::decode_32bit(uint32_t field_id, Proto32Bit value) {
   }
   return true;
 }
+void ExecuteServiceRequest::decode(const uint8_t *buffer, size_t length) {
+  uint32_t count_args = ProtoDecodableMessage::count_repeated_field(buffer, length, 2);
+  this->args.init(count_args);
+  ProtoDecodableMessage::decode(buffer, length);
+}
 #endif
 #ifdef USE_CAMERA
 void ListEntitiesCameraResponse::encode(ProtoWriteBuffer buffer) const {
diff --git a/esphome/components/api/api_pb2.h b/esphome/components/api/api_pb2.h
index 20866850a9..5433496d90 100644
--- a/esphome/components/api/api_pb2.h
+++ b/esphome/components/api/api_pb2.h
@@ -1279,10 +1279,11 @@ class ExecuteServiceArgument final : public ProtoDecodableMessage {
   float float_{0.0f};
   std::string string_{};
   int32_t int_{0};
-  std::vector<bool> bool_array{};
-  std::vector<int32_t> int_array{};
-  std::vector<float> float_array{};
-  std::vector<std::string> string_array{};
+  FixedVector<bool> bool_array{};
+  FixedVector<int32_t> int_array{};
+  FixedVector<float> float_array{};
+  FixedVector<std::string> string_array{};
+  void decode(const uint8_t *buffer, size_t length) override;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   void dump_to(std::string &out) const override;
 #endif
@@ -1300,7 +1301,8 @@ class ExecuteServiceRequest final : public ProtoDecodableMessage {
   const char *message_name() const override { return "execute_service_request"; }
 #endif
   uint32_t key{0};
-  std::vector<ExecuteServiceArgument> args{};
+  FixedVector<ExecuteServiceArgument> args{};
+  void decode(const uint8_t *buffer, size_t length) override;
 #ifdef HAS_PROTO_MESSAGE_DUMP
   void dump_to(std::string &out) const override;
 #endif
diff --git a/esphome/components/api/proto.cpp b/esphome/components/api/proto.cpp
index afda5d32ba..f99e5b66e5 100644
--- a/esphome/components/api/proto.cpp
+++ b/esphome/components/api/proto.cpp
@@ -7,6 +7,69 @@ namespace esphome::api {
 
 static const char *const TAG = "api.proto";
 
+uint32_t ProtoDecodableMessage::count_repeated_field(const uint8_t *buffer, size_t length, uint32_t target_field_id) {
+  uint32_t count = 0;
+  const uint8_t *ptr = buffer;
+  const uint8_t *end = buffer + length;
+
+  while (ptr < end) {
+    uint32_t consumed;
+
+    // Parse field header (tag)
+    auto res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
+    if (!res.has_value()) {
+      break;  // Invalid data, stop counting
+    }
+
+    uint32_t tag = res->as_uint32();
+    uint32_t field_type = tag & 0b111;
+    uint32_t field_id = tag >> 3;
+    ptr += consumed;
+
+    // Count if this is the target field
+    if (field_id == target_field_id) {
+      count++;
+    }
+
+    // Skip field data based on wire type
+    switch (field_type) {
+      case 0: {  // VarInt - parse and skip
+        res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
+        if (!res.has_value()) {
+          return count;  // Invalid data, return what we have
+        }
+        ptr += consumed;
+        break;
+      }
+      case 2: {  // Length-delimited - parse length and skip data
+        res = ProtoVarInt::parse(ptr, end - ptr, &consumed);
+        if (!res.has_value()) {
+          return count;
+        }
+        uint32_t field_length = res->as_uint32();
+        ptr += consumed;
+        if (ptr + field_length > end) {
+          return count;  // Out of bounds
+        }
+        ptr += field_length;
+        break;
+      }
+      case 5: {  // 32-bit - skip 4 bytes
+        if (ptr + 4 > end) {
+          return count;
+        }
+        ptr += 4;
+        break;
+      }
+      default:
+        // Unknown wire type, can't continue
+        return count;
+    }
+  }
+
+  return count;
+}
+
 void ProtoDecodableMessage::decode(const uint8_t *buffer, size_t length) {
   const uint8_t *ptr = buffer;
   const uint8_t *end = buffer + length;
diff --git a/esphome/components/api/proto.h b/esphome/components/api/proto.h
index a6a09bf7c5..50f85fb247 100644
--- a/esphome/components/api/proto.h
+++ b/esphome/components/api/proto.h
@@ -354,7 +354,18 @@ class ProtoMessage {
 // Base class for messages that support decoding
 class ProtoDecodableMessage : public ProtoMessage {
  public:
-  void decode(const uint8_t *buffer, size_t length);
+  virtual void decode(const uint8_t *buffer, size_t length);
+
+  /**
+   * Count occurrences of a repeated field in a protobuf buffer.
+   * This is a lightweight scan that only parses tags and skips field data.
+   *
+   * @param buffer Pointer to the protobuf buffer
+   * @param length Length of the buffer in bytes
+   * @param target_field_id The field ID to count
+   * @return Number of times the field appears in the buffer
+   */
+  static uint32_t count_repeated_field(const uint8_t *buffer, size_t length, uint32_t target_field_id);
 
  protected:
   virtual bool decode_varint(uint32_t field_id, ProtoVarInt value) { return false; }
diff --git a/esphome/components/api/user_services.cpp b/esphome/components/api/user_services.cpp
index 27b30eb332..3cbf2ab5f9 100644
--- a/esphome/components/api/user_services.cpp
+++ b/esphome/components/api/user_services.cpp
@@ -12,16 +12,16 @@ template<> int32_t get_execute_arg_value<int32_t>(const ExecuteServiceArgument &
 template<> float get_execute_arg_value<float>(const ExecuteServiceArgument &arg) { return arg.float_; }
 template<> std::string get_execute_arg_value<std::string>(const ExecuteServiceArgument &arg) { return arg.string_; }
 template<> std::vector<bool> get_execute_arg_value<std::vector<bool>>(const ExecuteServiceArgument &arg) {
-  return arg.bool_array;
+  return std::vector<bool>(arg.bool_array.begin(), arg.bool_array.end());
 }
 template<> std::vector<int32_t> get_execute_arg_value<std::vector<int32_t>>(const ExecuteServiceArgument &arg) {
-  return arg.int_array;
+  return std::vector<int32_t>(arg.int_array.begin(), arg.int_array.end());
 }
 template<> std::vector<float> get_execute_arg_value<std::vector<float>>(const ExecuteServiceArgument &arg) {
-  return arg.float_array;
+  return std::vector<float>(arg.float_array.begin(), arg.float_array.end());
 }
 template<> std::vector<std::string> get_execute_arg_value<std::vector<std::string>>(const ExecuteServiceArgument &arg) {
-  return arg.string_array;
+  return std::vector<std::string>(arg.string_array.begin(), arg.string_array.end());
 }
 
 template<> enums::ServiceArgType to_service_arg_type<bool>() { return enums::SERVICE_ARG_TYPE_BOOL; }
diff --git a/esphome/components/api/user_services.h b/esphome/components/api/user_services.h
index 29843a2f78..9ca5e1093e 100644
--- a/esphome/components/api/user_services.h
+++ b/esphome/components/api/user_services.h
@@ -55,7 +55,7 @@ template<typename... Ts> class UserServiceBase : public UserServiceDescriptor {
 
  protected:
   virtual void execute(Ts... x) = 0;
-  template<int... S> void execute_(const std::vector<ExecuteServiceArgument> &args, seq<S...> type) {
+  template<typename ArgsContainer, int... S> void execute_(const ArgsContainer &args, seq<S...> type) {
     this->execute((get_execute_arg_value<Ts>(args[S]))...);
   }
 
diff --git a/script/api_protobuf/api_protobuf.py b/script/api_protobuf/api_protobuf.py
index 9a55f1d136..f58442ff01 100755
--- a/script/api_protobuf/api_protobuf.py
+++ b/script/api_protobuf/api_protobuf.py
@@ -1879,6 +1879,9 @@ def build_message_type(
         )
         public_content.append("#endif")
 
+    # Collect fixed_vector fields for custom decode generation
+    fixed_vector_fields = []
+
     for field in desc.field:
         # Skip deprecated fields completely
         if field.options.deprecated:
@@ -1910,6 +1913,14 @@ def build_message_type(
                 f"since we cannot trust or control the number of items received from clients."
             )
 
+        # Collect fixed_vector repeated fields for custom decode generation
+        if (
+            needs_decode
+            and field.label == 3
+            and get_field_opt(field, pb.fixed_vector, False)
+        ):
+            fixed_vector_fields.append((field.name, field.number))
+
         ti = create_field_type_info(field, needs_decode, needs_encode)
 
         # Skip field declarations for fields that are in the base class
@@ -2018,6 +2029,22 @@ def build_message_type(
         prot = "bool decode_64bit(uint32_t field_id, Proto64Bit value) override;"
         protected_content.insert(0, prot)
 
+    # Generate custom decode() override for messages with FixedVector fields
+    if fixed_vector_fields:
+        # Generate the decode() implementation in cpp
+        o = f"void {desc.name}::decode(const uint8_t *buffer, size_t length) {{\n"
+        # Count and init each FixedVector field
+        for field_name, field_number in fixed_vector_fields:
+            o += f"  uint32_t count_{field_name} = ProtoDecodableMessage::count_repeated_field(buffer, length, {field_number});\n"
+            o += f"  this->{field_name}.init(count_{field_name});\n"
+        # Call parent decode to populate the fields
+        o += "  ProtoDecodableMessage::decode(buffer, length);\n"
+        o += "}\n"
+        cpp += o
+        # Generate the decode() declaration in header (public method)
+        prot = "void decode(const uint8_t *buffer, size_t length) override;"
+        public_content.append(prot)
+
     # Only generate encode method if this message needs encoding and has fields
     if needs_encode and encode:
         o = f"void {desc.name}::encode(ProtoWriteBuffer buffer) const {{"