diff --git a/esphome/components/api/proto.h b/esphome/components/api/proto.h
index b0c6299945..a18d5845b6 100644
--- a/esphome/components/api/proto.h
+++ b/esphome/components/api/proto.h
@@ -251,8 +251,16 @@ class ProtoWriteBuffer {
   /// Write a precomputed tag byte + 32-bit value in one operation.
   /// Tag must be a single-byte varint (< 128). No zero check.
   inline void write_tag_and_fixed32(uint8_t tag, uint32_t value) ESPHOME_ALWAYS_INLINE {
+    this->debug_check_bounds_(5);
     this->pos_[0] = tag;
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
     std::memcpy(this->pos_ + 1, &value, 4);
+#else
+    this->pos_[1] = static_cast<uint8_t>(value & 0xFF);
+    this->pos_[2] = static_cast<uint8_t>((value >> 8) & 0xFF);
+    this->pos_[3] = static_cast<uint8_t>((value >> 16) & 0xFF);
+    this->pos_[4] = static_cast<uint8_t>((value >> 24) & 0xFF);
+#endif
     this->pos_ += 5;
   }
   void encode_string(uint32_t field_id, const char *string, size_t len, bool force = false) {