diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index a0820e12283..df41c1a607d 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -55,6 +55,10 @@ repos:
   rev: v1.5.0
   hooks:
   - id: yesqa
+    additional_dependencies:
+      - flake8-docstrings==1.6.0
+      - flake8-no-implicit-concat==0.3.4
+      - flake8-requirements==1.7.8
 - repo: https://github.com/PyCQA/isort
   rev: '6.0.1'
   hooks:
diff --git a/CHANGES/11161.feature.rst b/CHANGES/11161.feature.rst
new file mode 100644
index 00000000000..617c4147a38
--- /dev/null
+++ b/CHANGES/11161.feature.rst
@@ -0,0 +1,2 @@
+Add support for Zstandard (aka Zstd) compression
+-- by :user:`KGuillaume-chaps`.
diff --git a/CONTRIBUTORS.txt b/CONTRIBUTORS.txt
index aa1f744b7a3..32c0747adf6 100644
--- a/CONTRIBUTORS.txt
+++ b/CONTRIBUTORS.txt
@@ -218,6 +218,7 @@ Justin Foo
 Justin Turner Arthur
 Kay Zheng
 Kevin Samuel
+Kilian Guillaume
 Kimmo Parviainen-Jalanko
 Kirill Klenov
 Kirill Malovitsa
diff --git a/aiohttp/_http_parser.pyx b/aiohttp/_http_parser.pyx
index 6bf125c06e9..f5015b297b0 100644
--- a/aiohttp/_http_parser.pyx
+++ b/aiohttp/_http_parser.pyx
@@ -437,7 +437,7 @@ cdef class HttpParser:
         if enc is not None:
             self._content_encoding = None
             enc = enc.lower()
-            if enc in ('gzip', 'deflate', 'br'):
+            if enc in ('gzip', 'deflate', 'br', 'zstd'):
                 encoding = enc
 
         if self._cparser.type == cparser.HTTP_REQUEST:
diff --git a/aiohttp/client_reqrep.py b/aiohttp/client_reqrep.py
index ff5ec9432de..e4d20f136cc 100644
--- a/aiohttp/client_reqrep.py
+++ b/aiohttp/client_reqrep.py
@@ -44,7 +44,7 @@
     InvalidURL,
     ServerFingerprintMismatch,
 )
-from .compression_utils import HAS_BROTLI
+from .compression_utils import HAS_BROTLI, HAS_ZSTD
 from .formdata import FormData
 from .hdrs import CONTENT_TYPE
 from .helpers import (
@@ -105,7 +105,15 @@
 
 
 def _gen_default_accept_encoding() -> str:
-    return "gzip, deflate, br" if HAS_BROTLI else "gzip, deflate"
+    encodings = [
+        "gzip",
+        "deflate",
+    ]
+    if HAS_BROTLI:
+        encodings.append("br")
+    if HAS_ZSTD:
+        encodings.append("zstd")
+    return ", ".join(encodings)
 
 
 @frozen_dataclass_decorator
diff --git a/aiohttp/compression_utils.py b/aiohttp/compression_utils.py
index 918b764baf5..9f5562ea1cb 100644
--- a/aiohttp/compression_utils.py
+++ b/aiohttp/compression_utils.py
@@ -21,6 +21,18 @@
 except ImportError:
     HAS_BROTLI = False
 
+if sys.version_info >= (3, 14):
+    import compression.zstd  # noqa: I900
+
+    HAS_ZSTD = True
+else:
+    try:
+        import zstandard
+
+        HAS_ZSTD = True
+    except ImportError:
+        HAS_ZSTD = False
+
 MAX_SYNC_CHUNK_SIZE = 1024
 
 
@@ -276,3 +288,22 @@ def flush(self) -> bytes:
         if hasattr(self._obj, "flush"):
             return cast(bytes, self._obj.flush())
         return b""
+
+
+class ZSTDDecompressor:
+    def __init__(self) -> None:
+        if not HAS_ZSTD:
+            raise RuntimeError(
+                "The zstd decompression is not available. "
+                "Please install `zstandard` module"
+            )
+        if sys.version_info >= (3, 14):
+            self._obj = compression.zstd.ZstdDecompressor()
+        else:
+            self._obj = zstandard.ZstdDecompressor()
+
+    def decompress_sync(self, data: bytes) -> bytes:
+        return self._obj.decompress(data)
+
+    def flush(self) -> bytes:
+        return b""
diff --git a/aiohttp/http_parser.py b/aiohttp/http_parser.py
index 8805319e309..fa0328830a2 100644
--- a/aiohttp/http_parser.py
+++ b/aiohttp/http_parser.py
@@ -26,7 +26,13 @@
 
 from . import hdrs
 from .base_protocol import BaseProtocol
-from .compression_utils import HAS_BROTLI, BrotliDecompressor, ZLibDecompressor
+from .compression_utils import (
+    HAS_BROTLI,
+    HAS_ZSTD,
+    BrotliDecompressor,
+    ZLibDecompressor,
+    ZSTDDecompressor,
+)
 from .helpers import (
     _EXC_SENTINEL,
     DEBUG,
@@ -527,7 +533,7 @@ def parse_headers(
         enc = headers.get(hdrs.CONTENT_ENCODING)
         if enc:
             enc = enc.lower()
-            if enc in ("gzip", "deflate", "br"):
+            if enc in ("gzip", "deflate", "br", "zstd"):
                 encoding = enc
 
         # chunking
@@ -930,7 +936,7 @@ def __init__(self, out: StreamReader, encoding: Optional[str]) -> None:
         self.encoding = encoding
         self._started_decoding = False
 
-        self.decompressor: Union[BrotliDecompressor, ZLibDecompressor]
+        self.decompressor: Union[BrotliDecompressor, ZLibDecompressor, ZSTDDecompressor]
         if encoding == "br":
             if not HAS_BROTLI:
                 raise ContentEncodingError(
@@ -938,6 +944,13 @@ def __init__(self, out: StreamReader, encoding: Optional[str]) -> None:
                     "Please install `Brotli`"
                 )
             self.decompressor = BrotliDecompressor()
+        elif encoding == "zstd":
+            if not HAS_ZSTD:
+                raise ContentEncodingError(
+                    "Can not decode content-encoding: zstandard (zstd). "
+                    "Please install `zstandard`"
+                )
+            self.decompressor = ZSTDDecompressor()
         else:
             self.decompressor = ZLibDecompressor(encoding=encoding)
 
diff --git a/docs/client_quickstart.rst b/docs/client_quickstart.rst
index 95d5b6bf2c4..48f123b94bd 100644
--- a/docs/client_quickstart.rst
+++ b/docs/client_quickstart.rst
@@ -190,6 +190,10 @@ You can enable ``brotli`` transfer-encodings support,
 just install `Brotli <https://pypi.org/project/Brotli/>`_
 or `brotlicffi <https://pypi.org/project/brotlicffi/>`_.
 
+You can enable ``zstd`` transfer-encodings support,
+install `zstandard <https://pypi.org/project/zstandard/>`_.
+If you are using Python >= 3.14, no dependency should be required.
+
 JSON Request
 ============
 
diff --git a/docs/spelling_wordlist.txt b/docs/spelling_wordlist.txt
index 79a2b5075f5..c3863fb41c5 100644
--- a/docs/spelling_wordlist.txt
+++ b/docs/spelling_wordlist.txt
@@ -382,3 +382,5 @@ www
 xxx
 yarl
 zlib
+zstandard
+zstd
diff --git a/requirements/lint.in b/requirements/lint.in
index 21a9fb4e0f4..e36b5f28cd6 100644
--- a/requirements/lint.in
+++ b/requirements/lint.in
@@ -14,3 +14,4 @@ trustme
 uvloop; platform_system != "Windows"
 valkey
 zlib_ng
+zstandard; implementation_name == "cpython"
diff --git a/requirements/lint.txt b/requirements/lint.txt
index bf329ee199a..02a73831cb7 100644
--- a/requirements/lint.txt
+++ b/requirements/lint.txt
@@ -1,5 +1,5 @@
 #
-# This file is autogenerated by pip-compile with python 3.10
+# This file is autogenerated by pip-compile with Python 3.12
 # by the following command:
 #
 #    pip-compile --allow-unsafe --output-file=requirements/lint.txt --strip-extras requirements/lint.in
@@ -8,8 +8,6 @@ aiodns==3.5.0
     # via -r requirements/lint.in
 annotated-types==0.7.0
     # via pydantic
-async-timeout==5.0.1
-    # via valkey
 blockbuster==1.5.24
     # via -r requirements/lint.in
 cffi==1.17.1
@@ -25,8 +23,6 @@ cryptography==45.0.4
     # via trustme
 distlib==0.3.9
     # via virtualenv
-exceptiongroup==1.3.0
-    # via pytest
 filelock==3.18.0
     # via virtualenv
 forbiddenfruit==0.1.4
@@ -94,21 +90,14 @@ six==1.17.0
     # via python-dateutil
 slotscheck==0.19.1
     # via -r requirements/lint.in
-tomli==2.2.1
-    # via
-    #   mypy
-    #   pytest
-    #   slotscheck
 trustme==1.2.1
     # via -r requirements/lint.in
 typing-extensions==4.14.0
     # via
-    #   exceptiongroup
     #   mypy
     #   pydantic
     #   pydantic-core
     #   python-on-whales
-    #   rich
     #   typing-inspection
 typing-inspection==0.4.1
     # via pydantic
@@ -120,3 +109,5 @@ virtualenv==20.31.2
     # via pre-commit
 zlib-ng==0.5.1
     # via -r requirements/lint.in
+zstandard==0.23.0 ; implementation_name == "cpython"
+    # via -r requirements/lint.in
diff --git a/requirements/runtime-deps.in b/requirements/runtime-deps.in
index 268ace3c9c7..cf0951e7276 100644
--- a/requirements/runtime-deps.in
+++ b/requirements/runtime-deps.in
@@ -10,3 +10,4 @@ frozenlist >= 1.1.1
 multidict >=4.5, < 7.0
 propcache >= 0.2.0
 yarl >= 1.17.0, < 2.0
+zstandard; platform_python_implementation == 'CPython' and python_version < "3.14"
diff --git a/requirements/runtime-deps.txt b/requirements/runtime-deps.txt
index a9e91e0bf9e..5fb79a21aa3 100644
--- a/requirements/runtime-deps.txt
+++ b/requirements/runtime-deps.txt
@@ -1,5 +1,5 @@
 #
-# This file is autogenerated by pip-compile with Python 3.10
+# This file is autogenerated by pip-compile with Python 3.12
 # by the following command:
 #
 #    pip-compile --allow-unsafe --output-file=requirements/runtime-deps.txt --strip-extras requirements/runtime-deps.in
@@ -10,8 +10,6 @@ aiohappyeyeballs==2.6.1
     # via -r requirements/runtime-deps.in
 aiosignal==1.3.2
     # via -r requirements/runtime-deps.in
-async-timeout==5.0.1 ; python_version < "3.11"
-    # via -r requirements/runtime-deps.in
 brotli==1.1.0 ; platform_python_implementation == "CPython"
     # via -r requirements/runtime-deps.in
 cffi==1.17.1
@@ -38,3 +36,5 @@ typing-extensions==4.14.0
     # via multidict
 yarl==1.20.1
     # via -r requirements/runtime-deps.in
+zstandard==0.23.0 ; platform_python_implementation == "CPython" and python_version < "3.14"
+    # via -r requirements/runtime-deps.in
diff --git a/setup.cfg b/setup.cfg
index c4ab069f396..21a8ca2e44f 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -67,6 +67,7 @@ speedups =
   aiodns >= 3.3.0
   Brotli; platform_python_implementation == 'CPython'
   brotlicffi; platform_python_implementation != 'CPython'
+  zstandard; platform_python_implementation == 'CPython' and python_version < "3.14"
 
 [options.packages.find]
 exclude =
diff --git a/tests/test_client_request.py b/tests/test_client_request.py
index 23b27556ab1..1852ebb1c81 100644
--- a/tests/test_client_request.py
+++ b/tests/test_client_request.py
@@ -358,7 +358,7 @@ def test_headers(make_request: _RequestMaker) -> None:
 
     assert hdrs.CONTENT_TYPE in req.headers
     assert req.headers[hdrs.CONTENT_TYPE] == "text/plain"
-    assert req.headers[hdrs.ACCEPT_ENCODING] == "gzip, deflate, br"
+    assert "gzip" in req.headers[hdrs.ACCEPT_ENCODING]
 
 
 def test_headers_list(make_request: _RequestMaker) -> None:
@@ -1568,15 +1568,20 @@ def test_loose_cookies_types(loop: asyncio.AbstractEventLoop) -> None:
 
 
 @pytest.mark.parametrize(
-    "has_brotli,expected",
+    "has_brotli,has_zstd,expected",
     [
-        (False, "gzip, deflate"),
-        (True, "gzip, deflate, br"),
+        (False, False, "gzip, deflate"),
+        (True, False, "gzip, deflate, br"),
+        (False, True, "gzip, deflate, zstd"),
+        (True, True, "gzip, deflate, br, zstd"),
     ],
 )
-def test_gen_default_accept_encoding(has_brotli: bool, expected: str) -> None:
+def test_gen_default_accept_encoding(
+    has_brotli: bool, has_zstd: bool, expected: str
+) -> None:
     with mock.patch("aiohttp.client_reqrep.HAS_BROTLI", has_brotli):
-        assert _gen_default_accept_encoding() == expected
+        with mock.patch("aiohttp.client_reqrep.HAS_ZSTD", has_zstd):
+            assert _gen_default_accept_encoding() == expected
 
 
 @pytest.mark.parametrize(
diff --git a/tests/test_http_parser.py b/tests/test_http_parser.py
index 6bb06159f21..fd7a52f0b88 100644
--- a/tests/test_http_parser.py
+++ b/tests/test_http_parser.py
@@ -2,6 +2,7 @@
 
 import asyncio
 import re
+import sys
 from contextlib import suppress
 from typing import Any, Dict, Iterable, List, Type
 from unittest import mock
@@ -34,6 +35,14 @@
 except ImportError:
     brotli = None
 
+if sys.version_info >= (3, 14):
+    import compression.zstd as zstandard  # noqa: I900
+else:
+    try:
+        import zstandard
+    except ImportError:
+        zstandard = None  # type: ignore[assignment]
+
 REQUEST_PARSERS = [HttpRequestParserPy]
 RESPONSE_PARSERS = [HttpResponseParserPy]
 
@@ -600,6 +609,14 @@ def test_compression_brotli(parser: HttpRequestParser) -> None:
     assert msg.compression == "br"
 
 
+@pytest.mark.skipif(zstandard is None, reason="zstandard is not installed")
+def test_compression_zstd(parser: HttpRequestParser) -> None:
+    text = b"GET /test HTTP/1.1\r\ncontent-encoding: zstd\r\n\r\n"
+    messages, upgrade, tail = parser.feed_data(text)
+    msg = messages[0][0]
+    assert msg.compression == "zstd"
+
+
 def test_compression_unknown(parser: HttpRequestParser) -> None:
     text = b"GET /test HTTP/1.1\r\ncontent-encoding: compress\r\n\r\n"
     messages, upgrade, tail = parser.feed_data(text)
@@ -1849,6 +1866,15 @@ async def test_http_payload_brotli(self, protocol: BaseProtocol) -> None:
         assert b"brotli data" == out._buffer[0]
         assert out.is_eof()
 
+    @pytest.mark.skipif(zstandard is None, reason="zstandard is not installed")
+    async def test_http_payload_zstandard(self, protocol: BaseProtocol) -> None:
+        compressed = zstandard.compress(b"zstd data")
+        out = aiohttp.StreamReader(protocol, 2**16, loop=asyncio.get_running_loop())
+        p = HttpPayloadParser(out, length=len(compressed), compression="zstd")
+        p.feed_data(compressed)
+        assert b"zstd data" == out._buffer[0]
+        assert out.is_eof()
+
 
 class TestDeflateBuffer:
     async def test_feed_data(self, protocol: BaseProtocol) -> None:
@@ -1919,6 +1945,18 @@ async def test_feed_eof_no_err_brotli(self, protocol: BaseProtocol) -> None:
         dbuf.feed_eof()
         assert [b"line"] == list(buf._buffer)
 
+    @pytest.mark.skipif(zstandard is None, reason="zstandard is not installed")
+    async def test_feed_eof_no_err_zstandard(self, protocol: BaseProtocol) -> None:
+        buf = aiohttp.StreamReader(protocol, 2**16, loop=asyncio.get_running_loop())
+        dbuf = DeflateBuffer(buf, "zstd")
+
+        dbuf.decompressor = mock.Mock()
+        dbuf.decompressor.flush.return_value = b"line"
+        dbuf.decompressor.eof = False
+
+        dbuf.feed_eof()
+        assert [b"line"] == list(buf._buffer)
+
     async def test_empty_body(self, protocol: BaseProtocol) -> None:
         buf = aiohttp.StreamReader(protocol, 2**16, loop=asyncio.get_running_loop())
         dbuf = DeflateBuffer(buf, "deflate")