diff --git a/CHANGES/9838.misc.rst b/CHANGES/9838.misc.rst
new file mode 100644
index 00000000000..dc41fae1c53
--- /dev/null
+++ b/CHANGES/9838.misc.rst
@@ -0,0 +1 @@
+Improved performance of writing chunked payloads by reducing memory copy -- by :user:`bdraco`.
diff --git a/aiohttp/http_writer.py b/aiohttp/http_writer.py
index a1a9860b48d..3f2a4ecda5f 100644
--- a/aiohttp/http_writer.py
+++ b/aiohttp/http_writer.py
@@ -110,8 +110,9 @@ async def write(
 
         if chunk:
             if self.chunked:
-                chunk_len_pre = ("%x\r\n" % len(chunk)).encode("ascii")
-                chunk = chunk_len_pre + chunk + b"\r\n"
+                chunk = b"".join(
+                    (f"{len(chunk):x}\r\n".encode("ascii"), chunk, b"\r\n")
+                )
 
             self._write(chunk)
 
@@ -147,13 +148,15 @@ async def write_eof(self, chunk: bytes = b"") -> None:
 
             chunk += self._compress.flush()
             if chunk and self.chunked:
-                chunk_len = ("%x\r\n" % len(chunk)).encode("ascii")
-                chunk = chunk_len + chunk + b"\r\n0\r\n\r\n"
+                chunk = b"".join(
+                    (f"{len(chunk):x}\r\n".encode("ascii"), chunk, b"\r\n0\r\n\r\n")
+                )
         else:
             if self.chunked:
                 if chunk:
-                    chunk_len = ("%x\r\n" % len(chunk)).encode("ascii")
-                    chunk = chunk_len + chunk + b"\r\n0\r\n\r\n"
+                    chunk = b"".join(
+                        (f"{len(chunk):x}\r\n".encode("ascii"), chunk, b"\r\n0\r\n\r\n")
+                    )
                 else:
                     chunk = b"0\r\n\r\n"