diff --git a/CHANGES/11623.bugfix b/CHANGES/11623.bugfix
new file mode 100644
index 00000000000..447dd56388c
--- /dev/null
+++ b/CHANGES/11623.bugfix
@@ -0,0 +1 @@
+Switched to `backports.zstd` for Python <3.14 and fixed zstd decompression for chunked zstd streams -- by :user:`ZhaoMJ`.
diff --git a/CONTRIBUTORS.txt b/CONTRIBUTORS.txt
index b64d99fb632..84692200b6e 100644
--- a/CONTRIBUTORS.txt
+++ b/CONTRIBUTORS.txt
@@ -270,6 +270,7 @@ Mikhail Burshteyn
 Mikhail Kashkin
 Mikhail Lukyanchenko
 Mikhail Nacharov
+Mingjie Zhao
 Misha Behersky
 Mitchell Ferree
 Morgan Delahaye-Prat
diff --git a/aiohttp/compression_utils.py b/aiohttp/compression_utils.py
index fcaee591fe5..c6c6f0d71fc 100644
--- a/aiohttp/compression_utils.py
+++ b/aiohttp/compression_utils.py
@@ -22,18 +22,14 @@
     HAS_BROTLI = False
 
 try:
-    from compression.zstd import (  # type: ignore[import-not-found]  # noqa: I900
-        ZstdDecompressor,
-    )
+    if sys.version_info >= (3, 14):
+        from compression.zstd import ZstdDecompressor  # noqa: I900
+    else:  # TODO(PY314): Remove mentions of backports.zstd across codebase
+        from backports.zstd import ZstdDecompressor
 
     HAS_ZSTD = True
 except ImportError:
-    try:
-        from zstandard import ZstdDecompressor
-
-        HAS_ZSTD = True
-    except ImportError:
-        HAS_ZSTD = False
+    HAS_ZSTD = False
 
 
 MAX_SYNC_CHUNK_SIZE = 1024
@@ -298,12 +294,12 @@ def __init__(self) -> None:
         if not HAS_ZSTD:
             raise RuntimeError(
                 "The zstd decompression is not available. "
-                "Please install `zstandard` module"
+                "Please install `backports.zstd` module"
             )
         self._obj = ZstdDecompressor()
 
     def decompress_sync(self, data: bytes) -> bytes:
-        return self._obj.decompress(data)  # type: ignore[no-any-return]
+        return self._obj.decompress(data)
 
     def flush(self) -> bytes:
         return b""
diff --git a/aiohttp/http_parser.py b/aiohttp/http_parser.py
index ce143819141..9e4d5a9ce0c 100644
--- a/aiohttp/http_parser.py
+++ b/aiohttp/http_parser.py
@@ -938,7 +938,7 @@ def __init__(self, out: StreamReader, encoding: str | None) -> None:
             if not HAS_ZSTD:
                 raise ContentEncodingError(
                     "Can not decode content-encoding: zstandard (zstd). "
-                    "Please install `zstandard`"
+                    "Please install `backports.zstd`"
                 )
             self.decompressor = ZSTDDecompressor()
         else:
diff --git a/docs/client_quickstart.rst b/docs/client_quickstart.rst
index 48f123b94bd..fc6d3875ea1 100644
--- a/docs/client_quickstart.rst
+++ b/docs/client_quickstart.rst
@@ -191,7 +191,7 @@ 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/>`_.
+install `backports.zstd <https://pypi.org/project/backports.zstd/>`_.
 If you are using Python >= 3.14, no dependency should be required.
 
 JSON Request
diff --git a/requirements/base-ft.txt b/requirements/base-ft.txt
index 5615e306c84..a851bf38281 100644
--- a/requirements/base-ft.txt
+++ b/requirements/base-ft.txt
@@ -12,6 +12,8 @@ aiosignal==1.4.0
     # via -r requirements/runtime-deps.in
 async-timeout==5.0.1 ; python_version < "3.11"
     # via -r requirements/runtime-deps.in
+backports-zstd==0.5.0 ; platform_python_implementation == "CPython" and python_version < "3.14"
+    # via -r requirements/runtime-deps.in
 brotli==1.1.0 ; platform_python_implementation == "CPython"
     # via -r requirements/runtime-deps.in
 cffi==2.0.0
@@ -30,7 +32,7 @@ multidict==6.7.0
     #   yarl
 packaging==25.0
     # via gunicorn
-propcache==0.4.0
+propcache==0.4.1
     # via
     #   -r requirements/runtime-deps.in
     #   yarl
@@ -42,7 +44,5 @@ typing-extensions==4.15.0
     # via
     #   aiosignal
     #   multidict
-yarl==1.21.0
-    # via -r requirements/runtime-deps.in
-zstandard==0.25.0 ; platform_python_implementation == "CPython" and python_version < "3.14"
+yarl==1.22.0
     # via -r requirements/runtime-deps.in
diff --git a/requirements/base.txt b/requirements/base.txt
index f3e3fe2649b..7e9da23c158 100644
--- a/requirements/base.txt
+++ b/requirements/base.txt
@@ -12,6 +12,8 @@ aiosignal==1.4.0
     # via -r requirements/runtime-deps.in
 async-timeout==5.0.1 ; python_version < "3.11"
     # via -r requirements/runtime-deps.in
+backports-zstd==0.5.0 ; platform_python_implementation == "CPython" and python_version < "3.14"
+    # via -r requirements/runtime-deps.in
 brotli==1.1.0 ; platform_python_implementation == "CPython"
     # via -r requirements/runtime-deps.in
 cffi==2.0.0
@@ -30,7 +32,7 @@ multidict==6.7.0
     #   yarl
 packaging==25.0
     # via gunicorn
-propcache==0.4.0
+propcache==0.4.1
     # via
     #   -r requirements/runtime-deps.in
     #   yarl
@@ -44,7 +46,5 @@ typing-extensions==4.15.0
     #   multidict
 uvloop==0.21.0 ; platform_system != "Windows" and implementation_name == "cpython"
     # via -r requirements/base.in
-yarl==1.21.0
-    # via -r requirements/runtime-deps.in
-zstandard==0.25.0 ; platform_python_implementation == "CPython" and python_version < "3.14"
+yarl==1.22.0
     # via -r requirements/runtime-deps.in
diff --git a/requirements/constraints.txt b/requirements/constraints.txt
index fd73a37c401..50e5906ad55 100644
--- a/requirements/constraints.txt
+++ b/requirements/constraints.txt
@@ -24,6 +24,10 @@ async-timeout==5.0.1 ; python_version < "3.11"
     #   valkey
 babel==2.17.0
     # via sphinx
+backports-zstd==0.5.0 ; implementation_name == "cpython"
+    # via
+    #   -r requirements/lint.in
+    #   -r requirements/runtime-deps.in
 blockbuster==1.5.25
     # via
     #   -r requirements/lint.in
@@ -145,7 +149,7 @@ pluggy==1.6.0
     #   pytest-cov
 pre-commit==4.3.0
     # via -r requirements/lint.in
-propcache==0.4.0
+propcache==0.4.1
     # via
     #   -r requirements/runtime-deps.in
     #   yarl
@@ -293,16 +297,12 @@ wait-for-it==2.3.0
     # via -r requirements/test-common.in
 wheel==0.46.0
     # via pip-tools
-yarl==1.21.0
+yarl==1.22.0
     # via -r requirements/runtime-deps.in
 zlib-ng==1.0.0
     # via
     #   -r requirements/lint.in
     #   -r requirements/test-common.in
-zstandard==0.25.0 ; implementation_name == "cpython"
-    # via
-    #   -r requirements/lint.in
-    #   -r requirements/runtime-deps.in
 
 # The following packages are considered to be unsafe in a requirements file:
 pip==25.2
diff --git a/requirements/dev.txt b/requirements/dev.txt
index f0ac2f57a03..73a8fb911d2 100644
--- a/requirements/dev.txt
+++ b/requirements/dev.txt
@@ -24,6 +24,10 @@ async-timeout==5.0.1 ; python_version < "3.11"
     #   valkey
 babel==2.17.0
     # via sphinx
+backports-zstd==0.5.0 ; platform_python_implementation == "CPython" and python_version < "3.14"
+    # via
+    #   -r requirements/lint.in
+    #   -r requirements/runtime-deps.in
 blockbuster==1.5.25
     # via
     #   -r requirements/lint.in
@@ -142,7 +146,7 @@ pluggy==1.6.0
     #   pytest-cov
 pre-commit==4.3.0
     # via -r requirements/lint.in
-propcache==0.4.0
+propcache==0.4.1
     # via
     #   -r requirements/runtime-deps.in
     #   yarl
@@ -284,16 +288,12 @@ wait-for-it==2.3.0
     # via -r requirements/test-common.in
 wheel==0.46.0
     # via pip-tools
-yarl==1.21.0
+yarl==1.22.0
     # via -r requirements/runtime-deps.in
 zlib-ng==1.0.0
     # via
     #   -r requirements/lint.in
     #   -r requirements/test-common.in
-zstandard==0.25.0 ; platform_python_implementation == "CPython" and python_version < "3.14"
-    # via
-    #   -r requirements/lint.in
-    #   -r requirements/runtime-deps.in
 
 # The following packages are considered to be unsafe in a requirements file:
 pip==25.2
diff --git a/requirements/lint.in b/requirements/lint.in
index e36b5f28cd6..c83d1dcec88 100644
--- a/requirements/lint.in
+++ b/requirements/lint.in
@@ -1,4 +1,5 @@
 aiodns
+backports.zstd; implementation_name == "cpython"
 blockbuster
 freezegun
 isal
@@ -14,4 +15,3 @@ trustme
 uvloop; platform_system != "Windows"
 valkey
 zlib_ng
-zstandard; implementation_name == "cpython"
diff --git a/requirements/lint.txt b/requirements/lint.txt
index 087a2f63e90..dbe3dcf4013 100644
--- a/requirements/lint.txt
+++ b/requirements/lint.txt
@@ -123,5 +123,5 @@ virtualenv==20.34.0
     # via pre-commit
 zlib-ng==1.0.0
     # via -r requirements/lint.in
-zstandard==0.25.0 ; implementation_name == "cpython"
+backports.zstd==0.5.0 ; implementation_name == "cpython"
     # via -r requirements/lint.in
diff --git a/requirements/runtime-deps.in b/requirements/runtime-deps.in
index f849b448cf6..f6c6f2e8caa 100644
--- a/requirements/runtime-deps.in
+++ b/requirements/runtime-deps.in
@@ -4,10 +4,10 @@ aiodns >= 3.3.0
 aiohappyeyeballs >= 2.5.0
 aiosignal >= 1.4.0
 async-timeout >= 4.0, < 6.0 ; python_version < "3.11"
+backports.zstd; platform_python_implementation == 'CPython' and python_version < "3.14"
 Brotli; platform_python_implementation == 'CPython'
 brotlicffi; platform_python_implementation != 'CPython'
 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 9af01567e76..c97bd0cd4bb 100644
--- a/requirements/runtime-deps.txt
+++ b/requirements/runtime-deps.txt
@@ -12,6 +12,8 @@ aiosignal==1.4.0
     # via -r requirements/runtime-deps.in
 async-timeout==5.0.1 ; python_version < "3.11"
     # via -r requirements/runtime-deps.in
+backports-zstd==0.5.0 ; platform_python_implementation == "CPython" and python_version < "3.14"
+    # via -r requirements/runtime-deps.in
 brotli==1.1.0 ; platform_python_implementation == "CPython"
     # via -r requirements/runtime-deps.in
 cffi==2.0.0
@@ -26,7 +28,7 @@ multidict==6.7.0
     # via
     #   -r requirements/runtime-deps.in
     #   yarl
-propcache==0.4.0
+propcache==0.4.1
     # via
     #   -r requirements/runtime-deps.in
     #   yarl
@@ -38,7 +40,5 @@ typing-extensions==4.15.0
     # via
     #   aiosignal
     #   multidict
-yarl==1.21.0
-    # via -r requirements/runtime-deps.in
-zstandard==0.25.0 ; platform_python_implementation == "CPython" and python_version < "3.14"
+yarl==1.22.0
     # via -r requirements/runtime-deps.in
diff --git a/requirements/test-ft.txt b/requirements/test-ft.txt
index 83762508513..f1491d4ed03 100644
--- a/requirements/test-ft.txt
+++ b/requirements/test-ft.txt
@@ -14,6 +14,8 @@ annotated-types==0.7.0
     # via pydantic
 async-timeout==5.0.1 ; python_version < "3.11"
     # via -r requirements/runtime-deps.in
+backports-zstd==0.5.0 ; platform_python_implementation == "CPython" and python_version < "3.14"
+    # via -r requirements/runtime-deps.in
 blockbuster==1.5.25
     # via -r requirements/test-common.in
 brotli==1.1.0 ; platform_python_implementation == "CPython"
@@ -77,7 +79,7 @@ pluggy==1.6.0
     # via
     #   pytest
     #   pytest-cov
-propcache==0.4.0
+propcache==0.4.1
     # via
     #   -r requirements/runtime-deps.in
     #   yarl
@@ -142,9 +144,7 @@ typing-inspection==0.4.2
     # via pydantic
 wait-for-it==2.3.0
     # via -r requirements/test-common.in
-yarl==1.21.0
+yarl==1.22.0
     # via -r requirements/runtime-deps.in
 zlib-ng==1.0.0
     # via -r requirements/test-common.in
-zstandard==0.25.0 ; platform_python_implementation == "CPython" and python_version < "3.14"
-    # via -r requirements/runtime-deps.in
diff --git a/requirements/test.txt b/requirements/test.txt
index 101f2cb9018..7a149924182 100644
--- a/requirements/test.txt
+++ b/requirements/test.txt
@@ -14,6 +14,8 @@ annotated-types==0.7.0
     # via pydantic
 async-timeout==5.0.1 ; python_version < "3.11"
     # via -r requirements/runtime-deps.in
+backports-zstd==0.5.0 ; platform_python_implementation == "CPython" and python_version < "3.14"
+    # via -r requirements/runtime-deps.in
 blockbuster==1.5.25
     # via -r requirements/test-common.in
 brotli==1.1.0 ; platform_python_implementation == "CPython"
@@ -77,7 +79,7 @@ pluggy==1.6.0
     # via
     #   pytest
     #   pytest-cov
-propcache==0.4.0
+propcache==0.4.1
     # via
     #   -r requirements/runtime-deps.in
     #   yarl
@@ -144,9 +146,7 @@ uvloop==0.21.0 ; platform_system != "Windows" and implementation_name == "cpytho
     # via -r requirements/base.in
 wait-for-it==2.3.0
     # via -r requirements/test-common.in
-yarl==1.21.0
+yarl==1.22.0
     # via -r requirements/runtime-deps.in
 zlib-ng==1.0.0
     # via -r requirements/test-common.in
-zstandard==0.25.0 ; platform_python_implementation == "CPython" and python_version < "3.14"
-    # via -r requirements/runtime-deps.in
diff --git a/setup.cfg b/setup.cfg
index 7fd0f0c59c6..cd12bc3013c 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -69,7 +69,7 @@ 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"
+  backports.zstd; platform_python_implementation == 'CPython' and python_version < "3.14"
 
 [options.packages.find]
 exclude =
diff --git a/tests/test_http_parser.py b/tests/test_http_parser.py
index 4aa965e0ae4..3daff5cd206 100644
--- a/tests/test_http_parser.py
+++ b/tests/test_http_parser.py
@@ -37,13 +37,13 @@
 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]
+try:
+    if sys.version_info >= (3, 14):
+        import compression.zstd as zstandard  # noqa: I900
+    else:
+        import backports.zstd as zstandard
+except ImportError:
+    zstandard = None  # type: ignore[assignment]
 
 REQUEST_PARSERS = [HttpRequestParserPy]
 RESPONSE_PARSERS = [HttpResponseParserPy]