diff --git a/esphome/components/api/api_frame_helper_noise.cpp b/esphome/components/api/api_frame_helper_noise.cpp
index 54dca9ff3d4..fdc98aa24c0 100644
--- a/esphome/components/api/api_frame_helper_noise.cpp
+++ b/esphome/components/api/api_frame_helper_noise.cpp
@@ -207,9 +207,7 @@ APIError APINoiseFrameHelper::try_read_frame_() {
   // During handshake, rx_buf_.size() is used in prologue construction, so
   // the buffer must be exactly msg_size to avoid prologue mismatch.)
   uint16_t alloc_size = msg_size + (is_data ? RX_BUF_NULL_TERMINATOR : 0);
-  if (this->rx_buf_.size() != alloc_size) {
-    this->rx_buf_.resize(alloc_size);
-  }
+  this->rx_buf_.resize(alloc_size);
 
   if (rx_buf_len_ < msg_size) {
     // more data to read
diff --git a/esphome/components/api/api_frame_helper_plaintext.cpp b/esphome/components/api/api_frame_helper_plaintext.cpp
index 793cece3b82..007da7ef2b1 100644
--- a/esphome/components/api/api_frame_helper_plaintext.cpp
+++ b/esphome/components/api/api_frame_helper_plaintext.cpp
@@ -165,9 +165,7 @@ APIError APIPlaintextFrameHelper::try_read_frame_() {
 
   // Reserve space for body (+ null terminator so protobuf StringRef fields
   // can be safely null-terminated in-place after decode)
-  if (this->rx_buf_.size() != this->rx_header_parsed_len_ + RX_BUF_NULL_TERMINATOR) {
-    this->rx_buf_.resize(this->rx_header_parsed_len_ + RX_BUF_NULL_TERMINATOR);
-  }
+  this->rx_buf_.resize(this->rx_header_parsed_len_ + RX_BUF_NULL_TERMINATOR);
 
   if (rx_buf_len_ < rx_header_parsed_len_) {
     // more data to read