diff --git a/esphome/components/audio/audio_transfer_buffer.cpp b/esphome/components/audio/audio_transfer_buffer.cpp
index 790cd62db0..ddb669e0eb 100644
--- a/esphome/components/audio/audio_transfer_buffer.cpp
+++ b/esphome/components/audio/audio_transfer_buffer.cpp
@@ -2,6 +2,8 @@
 
 #ifdef USE_ESP32
 
+#include <cstring>
+
 #include "esphome/core/helpers.h"
 
 namespace esphome {
@@ -75,12 +77,32 @@ bool AudioTransferBuffer::has_buffered_data() const {
 }
 
 bool AudioTransferBuffer::reallocate(size_t new_buffer_size) {
-  if (this->buffer_length_ > 0) {
-    // Buffer currently has data, so reallocation is impossible
+  if (this->buffer_ == nullptr) {
+    return this->allocate_buffer_(new_buffer_size);
+  }
+
+  if (new_buffer_size < this->buffer_length_) {
+    // New size is too small to hold existing data
     return false;
   }
-  this->deallocate_buffer_();
-  return this->allocate_buffer_(new_buffer_size);
+
+  // Shift existing data to the start of the buffer so realloc preserves it
+  if ((this->buffer_length_ > 0) && (this->data_start_ != this->buffer_)) {
+    std::memmove(this->buffer_, this->data_start_, this->buffer_length_);
+    this->data_start_ = this->buffer_;
+  }
+
+  RAMAllocator<uint8_t> allocator;
+  uint8_t *new_buffer = allocator.reallocate(this->buffer_, new_buffer_size);
+  if (new_buffer == nullptr) {
+    // Reallocation failed, but the original buffer is still valid
+    return false;
+  }
+
+  this->buffer_ = new_buffer;
+  this->data_start_ = this->buffer_;
+  this->buffer_size_ = new_buffer_size;
+  return true;
 }
 
 bool AudioTransferBuffer::allocate_buffer_(size_t buffer_size) {
@@ -115,7 +137,7 @@ size_t AudioSourceTransferBuffer::transfer_data_from_source(TickType_t ticks_to_
   if (pre_shift) {
     // Shift data in buffer to start
     if (this->buffer_length_ > 0) {
-      memmove(this->buffer_, this->data_start_, this->buffer_length_);
+      std::memmove(this->buffer_, this->data_start_, this->buffer_length_);
     }
     this->data_start_ = this->buffer_;
   }
@@ -150,7 +172,7 @@ size_t AudioSinkTransferBuffer::transfer_data_to_sink(TickType_t ticks_to_wait,
 
   if (post_shift) {
     // Shift unwritten data to the start of the buffer
-    memmove(this->buffer_, this->data_start_, this->buffer_length_);
+    std::memmove(this->buffer_, this->data_start_, this->buffer_length_);
     this->data_start_ = this->buffer_;
   }
 
diff --git a/esphome/components/audio/audio_transfer_buffer.h b/esphome/components/audio/audio_transfer_buffer.h
index edb484e7d2..24c0670d1a 100644
--- a/esphome/components/audio/audio_transfer_buffer.h
+++ b/esphome/components/audio/audio_transfer_buffer.h
@@ -56,6 +56,9 @@ class AudioTransferBuffer {
   /// @return True if there is data, false otherwise.
   virtual bool has_buffered_data() const;
 
+  /// @brief Reallocates the transfer buffer, preserving any existing data.
+  /// @param new_buffer_size The new size in bytes. Must be at least as large as available().
+  /// @return True if successful, false otherwise. On failure, the original buffer remains valid.
   bool reallocate(size_t new_buffer_size);
 
  protected: