diff --git a/esphome/components/api/proto.h b/esphome/components/api/proto.h
index fea219ecb9..ccc6c0d52c 100644
--- a/esphome/components/api/proto.h
+++ b/esphome/components/api/proto.h
@@ -160,8 +160,7 @@ class ProtoWriteBuffer {
     this->encode_field_raw(field_id, 2);
     this->encode_varint_raw(len);
     auto *data = reinterpret_cast<const uint8_t *>(string);
-    for (size_t i = 0; i < len; i++)
-      this->write(data[i]);
+    this->buffer_->insert(this->buffer_->end(), data, data + len);
   }
   void encode_string(uint32_t field_id, const std::string &value, bool force = false) {
     this->encode_string(field_id, value.data(), value.size());