diff --git a/CHANGES/12499.deprecation.rst b/CHANGES/12499.deprecation.rst
new file mode 100644
index 00000000000..c9a5b533c77
--- /dev/null
+++ b/CHANGES/12499.deprecation.rst
@@ -0,0 +1,7 @@
+Deprecated :class:`~aiohttp.BasicAuth` and the ``auth`` / ``proxy_auth``
+parameters. They will be removed in aiohttp 4.0. Use the new
+:func:`~aiohttp.encode_basic_auth` helper together with
+``headers={"Authorization": ...}`` (or
+``proxy_headers={"Proxy-Authorization": ...}`` for proxies) instead.
+Note that ``encode_basic_auth()`` defaults to `utf-8`, not `latin1`
+-- by :user:`Dreamsorcerer`.
diff --git a/CHANGES/12499.feature.rst b/CHANGES/12499.feature.rst
new file mode 100644
index 00000000000..8b242432367
--- /dev/null
+++ b/CHANGES/12499.feature.rst
@@ -0,0 +1,3 @@
+Added :func:`~aiohttp.encode_basic_auth` for encoding HTTP Basic
+Authentication credentials. Replaces the now-deprecated
+:class:`~aiohttp.BasicAuth` -- by :user:`Dreamsorcerer`.
diff --git a/aiohttp/__init__.py b/aiohttp/__init__.py
index e01204a5adb..59fc64160f1 100644
--- a/aiohttp/__init__.py
+++ b/aiohttp/__init__.py
@@ -53,7 +53,7 @@
 from .connector import AddrInfoType, SocketFactoryType
 from .cookiejar import CookieJar, DummyCookieJar
 from .formdata import FormData
-from .helpers import BasicAuth, ChainMapProxy, ETag
+from .helpers import BasicAuth, ChainMapProxy, ETag, encode_basic_auth
 from .http import (
     HttpVersion,
     HttpVersion10,
@@ -172,6 +172,7 @@
     "ChainMapProxy",
     "DigestAuthMiddleware",
     "ETag",
+    "encode_basic_auth",
     "set_zlib_backend",
     # http
     "HttpVersion",
diff --git a/aiohttp/client.py b/aiohttp/client.py
index 6a9b084a7b3..eb2d5e880d5 100644
--- a/aiohttp/client.py
+++ b/aiohttp/client.py
@@ -394,6 +394,22 @@ def __init__(
         if cookies:
             self._cookie_jar.update_cookies(cookies)
 
+        if auth is not None:
+            warnings.warn(
+                "The 'auth' parameter is deprecated and will be removed in v4;"
+                " pass headers={'Authorization': "
+                "aiohttp.encode_basic_auth(login, password)} instead",
+                DeprecationWarning,
+                stacklevel=2,
+            )
+        if proxy_auth is not None:
+            warnings.warn(
+                "The 'proxy_auth' parameter is deprecated and will be removed in v4;"
+                " pass proxy_headers={'Proxy-Authorization': "
+                "aiohttp.encode_basic_auth(login, password)} instead",
+                DeprecationWarning,
+                stacklevel=2,
+            )
         self._connector_owner = connector_owner
         self._default_auth = auth
         self._version = version
@@ -516,6 +532,23 @@ async def _request(
         if self.closed:
             raise RuntimeError("Session is closed")
 
+        if auth is not None:
+            warnings.warn(
+                "The 'auth' parameter is deprecated and will be removed in v4;"
+                " pass headers={'Authorization': "
+                "aiohttp.encode_basic_auth(login, password)} instead",
+                DeprecationWarning,
+                stacklevel=3,
+            )
+        if proxy_auth is not None:
+            warnings.warn(
+                "The 'proxy_auth' parameter is deprecated and will be removed in v4;"
+                " pass proxy_headers={'Proxy-Authorization': "
+                "aiohttp.encode_basic_auth(login, password)} instead",
+                DeprecationWarning,
+                stacklevel=3,
+            )
+
         if not isinstance(ssl, SSL_ALLOWED_TYPES):
             raise TypeError(
                 "ssl should be SSLContext, Fingerprint, or bool, "
@@ -1065,6 +1098,22 @@ async def _ws_connect(
         max_msg_size: int = 4 * 1024 * 1024,
         decode_text: bool = True,
     ) -> "ClientWebSocketResponse[bool]":
+        if auth is not None:
+            warnings.warn(
+                "The 'auth' parameter is deprecated and will be removed in v4;"
+                " pass headers={'Authorization': "
+                "aiohttp.encode_basic_auth(login, password)} instead",
+                DeprecationWarning,
+                stacklevel=3,
+            )
+        if proxy_auth is not None:
+            warnings.warn(
+                "The 'proxy_auth' parameter is deprecated and will be removed in v4;"
+                " pass proxy_headers={'Proxy-Authorization': "
+                "aiohttp.encode_basic_auth(login, password)} instead",
+                DeprecationWarning,
+                stacklevel=3,
+            )
         if timeout is not sentinel:
             if isinstance(timeout, ClientWSTimeout):
                 ws_timeout = timeout
diff --git a/aiohttp/client_reqrep.py b/aiohttp/client_reqrep.py
index 815f9c2dd61..8c353822b58 100644
--- a/aiohttp/client_reqrep.py
+++ b/aiohttp/client_reqrep.py
@@ -41,6 +41,7 @@
     HeadersDictProxy,
     HeadersMixin,
     TimerNoop,
+    _basic_auth_no_warn,
     frozen_dataclass_decorator,
     is_expected_content_type,
     parse_mimetype,
@@ -807,7 +808,7 @@ def _update_host(self, url: URL) -> None:
 
         # basic auth info
         if url.raw_user or url.raw_password:
-            self.auth = BasicAuth(url.user or "", url.password or "")
+            self.auth = _basic_auth_no_warn(url.user or "", url.password or "")
 
     def _update_headers(self, headers: CIMultiDict[str]) -> None:
         """Update request headers."""
diff --git a/aiohttp/helpers.py b/aiohttp/helpers.py
index 3e5677a46bd..bb07a8f79a2 100644
--- a/aiohttp/helpers.py
+++ b/aiohttp/helpers.py
@@ -153,6 +153,18 @@
 json_re = re.compile(r"^(?:application/|[\w.-]+/[\w.+-]+?\+)json$", re.IGNORECASE)
 
 
+def encode_basic_auth(login: str, password: str = "", encoding: str = "utf-8") -> str:
+    """Encode HTTP Basic Authentication credentials as an Authorization header value.
+
+    Returns a string of the form ``"Basic <base64>"`` suitable for use as the
+    value of the ``Authorization`` (or ``Proxy-Authorization``) header.
+    """
+    if ":" in login:
+        raise ValueError('A ":" is not allowed in login (RFC 7617#section-2)')
+    creds = f"{login}:{password}".encode(encoding)
+    return "Basic " + base64.b64encode(creds).decode(encoding)
+
+
 class BasicAuth(namedtuple("BasicAuth", ["login", "password", "encoding"])):
     """Http basic authentication helper."""
 
@@ -168,6 +180,13 @@ def __new__(
         if ":" in login:
             raise ValueError('A ":" is not allowed in login (RFC 1945#section-11.1)')
 
+        warnings.warn(
+            "BasicAuth is deprecated and will be removed in aiohttp 4.0; "
+            "use aiohttp.encode_basic_auth() with "
+            "headers={'Authorization': ...} instead",
+            DeprecationWarning,
+            stacklevel=2,
+        )
         return super().__new__(cls, login, password, encoding)
 
     @classmethod
@@ -197,7 +216,7 @@ def decode(cls, auth_header: str, encoding: str = "latin1") -> "BasicAuth":
         except ValueError:
             raise ValueError("Invalid credentials.")
 
-        return cls(username, password, encoding=encoding)
+        return _basic_auth_no_warn(username, password, encoding)
 
     @classmethod
     def from_url(cls, url: URL, *, encoding: str = "latin1") -> Optional["BasicAuth"]:
@@ -208,12 +227,22 @@ def from_url(cls, url: URL, *, encoding: str = "latin1") -> Optional["BasicAuth"
         # to already have these values parsed from the netloc in the cache.
         if url.raw_user is None and url.raw_password is None:
             return None
-        return cls(url.user or "", url.password or "", encoding=encoding)
+        return _basic_auth_no_warn(url.user or "", url.password or "", encoding)
 
     def encode(self) -> str:
         """Encode credentials."""
-        creds = (f"{self.login}:{self.password}").encode(self.encoding)
-        return "Basic %s" % base64.b64encode(creds).decode(self.encoding)
+        return encode_basic_auth(self.login, self.password, self.encoding)
+
+
+def _basic_auth_no_warn(
+    login: str, password: str = "", encoding: str = "latin1"
+) -> BasicAuth:
+    """Construct a BasicAuth without emitting the deprecation warning.
+
+    For internal use only. Bypasses BasicAuth.__new__ so that aiohttp's own
+    machinery doesn't trigger deprecation warnings in user code.
+    """
+    return tuple.__new__(BasicAuth, (login, password, encoding))
 
 
 def strip_auth_from_url(url: URL) -> tuple[URL, BasicAuth | None]:
@@ -222,7 +251,7 @@ def strip_auth_from_url(url: URL) -> tuple[URL, BasicAuth | None]:
     # to already have these values parsed from the netloc in the cache.
     if url.raw_user is None and url.raw_password is None:
         return url, None
-    return url.with_user(None), BasicAuth(url.user or "", url.password or "")
+    return url.with_user(None), _basic_auth_no_warn(url.user or "", url.password or "")
 
 
 def netrc_from_env() -> netrc.netrc | None:
@@ -302,7 +331,7 @@ def basicauth_from_netrc(netrc_obj: netrc.netrc | None, host: str) -> BasicAuth:
     if password is None:
         password = ""  # type: ignore[unreachable]
 
-    return BasicAuth(username, password)
+    return _basic_auth_no_warn(username, password)
 
 
 def proxies_from_env() -> dict[str, ProxyInfo]:
diff --git a/docs/client_advanced.rst b/docs/client_advanced.rst
index dc0dfb3660e..bfea3295d1a 100644
--- a/docs/client_advanced.rst
+++ b/docs/client_advanced.rst
@@ -59,14 +59,21 @@ For ``text/plain``::
 Authentication
 --------------
 
-Instead of setting the ``Authorization`` header directly,
-:class:`ClientSession` and individual request methods provide an ``auth``
-argument. An instance of :class:`BasicAuth` can be passed in like this::
+For HTTP Basic Authentication, build the ``Authorization`` header using
+:func:`encode_basic_auth` and pass it via ``headers``::
 
-    auth = BasicAuth(login="...", password="...")
-    async with ClientSession(auth=auth) as session:
+    from aiohttp import ClientSession, encode_basic_auth
+
+    headers = {"Authorization": encode_basic_auth("user", "pass")}
+    async with ClientSession(headers=headers) as session:
         ...
 
+.. deprecated:: 3.14
+
+   The ``auth`` parameter and the :class:`BasicAuth` class are deprecated and
+   will be removed in 4.0. Use :func:`encode_basic_auth` together with the
+   ``headers`` parameter as shown above.
+
 For HTTP digest authentication, use the :class:`DigestAuthMiddleware` client middleware::
 
     from aiohttp import ClientSession, DigestAuthMiddleware
@@ -718,11 +725,13 @@ To connect, use the *proxy* parameter::
 
 It also supports proxy authorization::
 
+   from aiohttp import encode_basic_auth
+
    async with aiohttp.ClientSession() as session:
-       proxy_auth = aiohttp.BasicAuth('user', 'pass')
+       proxy_headers = {"Proxy-Authorization": encode_basic_auth("user", "pass")}
        async with session.get("http://python.org",
                               proxy="http://proxy.com",
-                              proxy_auth=proxy_auth) as resp:
+                              proxy_headers=proxy_headers) as resp:
            print(resp.status)
 
 Authentication credentials can be passed in proxy URL::
@@ -732,11 +741,19 @@ Authentication credentials can be passed in proxy URL::
 
 And you may set default proxy::
 
-   proxy_auth = aiohttp.BasicAuth('user', 'pass')
-   async with aiohttp.ClientSession(proxy="http://proxy.com", proxy_auth=proxy_auth) as session:
+   proxy_headers = {"Proxy-Authorization": encode_basic_auth("user", "pass")}
+   async with aiohttp.ClientSession(
+       proxy="http://proxy.com", proxy_headers=proxy_headers
+   ) as session:
        async with session.get("http://python.org") as resp:
            print(resp.status)
 
+.. deprecated:: 3.14
+
+   The ``proxy_auth`` parameter is deprecated and will be removed in 4.0. Use
+   :func:`encode_basic_auth` with ``proxy_headers={"Proxy-Authorization": ...}``
+   as shown above.
+
 Contrary to the ``requests`` library, it won't read environment
 variables by default. But you can do so by passing
 ``trust_env=True`` into :class:`aiohttp.ClientSession`
diff --git a/docs/client_reference.rst b/docs/client_reference.rst
index ccbac8b6885..657b463a1a8 100644
--- a/docs/client_reference.rst
+++ b/docs/client_reference.rst
@@ -2326,6 +2326,22 @@ Utilities
 
 
 
+.. function:: encode_basic_auth(login, password='', encoding='utf-8')
+
+   Encode HTTP Basic Authentication credentials as a value suitable for the
+   ``Authorization`` (or ``Proxy-Authorization``) header::
+
+       headers = {"Authorization": encode_basic_auth("user", "pass")}
+
+   :param str login: login
+   :param str password: password (``''`` by default)
+   :param str encoding: encoding (``'utf-8'`` by default)
+   :return: a string of the form ``"Basic <base64-encoded credentials>"``
+   :rtype: str
+
+   .. versionadded:: 3.14
+
+
 .. class:: BasicAuth(login, password='', encoding='latin1')
    :canonical: aiohttp.helpers.BasicAuth
 
@@ -2336,9 +2352,17 @@ Utilities
    :param str encoding: encoding (``'latin1'`` by default)
 
 
-   Should be used for specifying authorization data in client API,
+   Previously this was used for specifying authorization data in client API,
    e.g. *auth* parameter for :meth:`ClientSession.request() <aiohttp.ClientSession.request>`.
 
+   .. deprecated:: 3.14
+
+      Constructing :class:`BasicAuth` is deprecated and will be removed in
+      4.0. Use :func:`encode_basic_auth` together with the ``headers``
+      parameter (or ``proxy_headers`` for proxies) instead. The
+      :meth:`decode` and :meth:`from_url` class methods remain available for
+      parsing.
+
 
    .. classmethod:: decode(auth_header, encoding='latin1')
 
diff --git a/tests/test_client_functional.py b/tests/test_client_functional.py
index b6efc7e07c9..9c8e274bab3 100644
--- a/tests/test_client_functional.py
+++ b/tests/test_client_functional.py
@@ -65,6 +65,16 @@
 from aiohttp.test_utils import TestClient, TestServer
 from aiohttp.typedefs import Handler
 
+pytestmark = [
+    pytest.mark.filterwarnings(r"ignore:BasicAuth is deprecated:DeprecationWarning"),
+    pytest.mark.filterwarnings(
+        r"ignore:The 'auth' parameter is deprecated:DeprecationWarning"
+    ),
+    pytest.mark.filterwarnings(
+        r"ignore:The 'proxy_auth' parameter is deprecated:DeprecationWarning"
+    ),
+]
+
 
 @pytest.fixture
 def here() -> pathlib.Path:
diff --git a/tests/test_client_request.py b/tests/test_client_request.py
index bc72704ff28..08d075bbba4 100644
--- a/tests/test_client_request.py
+++ b/tests/test_client_request.py
@@ -457,19 +457,17 @@ async def test_ipv6_nondefault_https_port(make_client_request: _RequestMaker) ->
 
 
 async def test_basic_auth(make_client_request: _RequestMaker) -> None:
-    req = make_client_request(
-        "get", URL("http://python.org"), auth=aiohttp.BasicAuth("nkim", "1234")
-    )
+    with pytest.warns(DeprecationWarning, match="BasicAuth is deprecated"):
+        auth = aiohttp.BasicAuth("nkim", "1234")
+    req = make_client_request("get", URL("http://python.org"), auth=auth)
     assert "AUTHORIZATION" in req.headers
     assert "Basic bmtpbToxMjM0" == req.headers["AUTHORIZATION"]
 
 
 async def test_basic_auth_utf8(make_client_request: _RequestMaker) -> None:
-    req = make_client_request(
-        "get",
-        URL("http://python.org"),
-        auth=aiohttp.BasicAuth("nkim", "секрет", "utf-8"),
-    )
+    with pytest.warns(DeprecationWarning, match="BasicAuth is deprecated"):
+        auth = aiohttp.BasicAuth("nkim", "секрет", "utf-8")
+    req = make_client_request("get", URL("http://python.org"), auth=auth)
     assert "AUTHORIZATION" in req.headers
     assert "Basic bmtpbTrRgdC10LrRgNC10YI=" == req.headers["AUTHORIZATION"]
 
@@ -496,9 +494,9 @@ async def test_basic_auth_no_user_from_url(make_client_request: _RequestMaker) -
 async def test_basic_auth_from_url_overridden(
     make_client_request: _RequestMaker,
 ) -> None:
-    req = make_client_request(
-        "get", URL("http://garbage@python.org"), auth=aiohttp.BasicAuth("nkim", "1234")
-    )
+    with pytest.warns(DeprecationWarning, match="BasicAuth is deprecated"):
+        auth = aiohttp.BasicAuth("nkim", "1234")
+    req = make_client_request("get", URL("http://garbage@python.org"), auth=auth)
     assert "AUTHORIZATION" in req.headers
     assert "Basic bmtpbToxMjM0" == req.headers["AUTHORIZATION"]
     assert "python.org" == req.url.host
diff --git a/tests/test_client_session.py b/tests/test_client_session.py
index 959c1c166bb..dc46b20fd05 100644
--- a/tests/test_client_session.py
+++ b/tests/test_client_session.py
@@ -892,6 +892,9 @@ async def test_proxy_str(session: ClientSession, params: _Params) -> None:
     ]
 
 
+@pytest.mark.filterwarnings(
+    r"ignore:The 'proxy_auth' parameter is deprecated:DeprecationWarning"
+)
 async def test_default_proxy() -> None:
     proxy_url = URL("http://proxy.example.com")
     proxy_auth = mock.Mock()
@@ -1497,6 +1500,10 @@ async def test_netrc_auth_from_home_directory(auth_server: TestServer) -> None:
 
 
 @pytest.mark.usefixtures("netrc_default_contents")
+@pytest.mark.filterwarnings(
+    r"ignore:The 'auth' parameter is deprecated:DeprecationWarning",
+    r"ignore:BasicAuth is deprecated:DeprecationWarning",
+)
 async def test_netrc_auth_overridden_by_explicit_auth(auth_server: TestServer) -> None:
     """Test that explicit auth parameter overrides netrc authentication."""
     async with (
@@ -1511,6 +1518,24 @@ async def test_netrc_auth_overridden_by_explicit_auth(auth_server: TestServer) -
         assert text == "auth:Basic ZXhwbGljaXRfdXNlcjpleHBsaWNpdF9wYXNz"
 
 
+async def test_client_session_auth_deprecated() -> None:
+    """ClientSession(auth=...) emits a DeprecationWarning."""
+    with pytest.warns(DeprecationWarning, match="'auth' parameter is deprecated"):
+        session = ClientSession(
+            auth=aiohttp.helpers._basic_auth_no_warn("user", "pass")
+        )
+    await session.close()
+
+
+async def test_client_session_proxy_auth_deprecated() -> None:
+    """ClientSession(proxy_auth=...) emits a DeprecationWarning."""
+    with pytest.warns(DeprecationWarning, match="'proxy_auth' parameter is deprecated"):
+        session = ClientSession(
+            proxy_auth=aiohttp.helpers._basic_auth_no_warn("user", "pass")
+        )
+    await session.close()
+
+
 @pytest.mark.usefixtures("netrc_other_host")
 async def test_netrc_auth_host_not_in_netrc(auth_server: TestServer) -> None:
     """Test that netrc lookup returns None when host is not in netrc file."""
diff --git a/tests/test_helpers.py b/tests/test_helpers.py
index a257a1d18f6..500dd89a849 100644
--- a/tests/test_helpers.py
+++ b/tests/test_helpers.py
@@ -3,6 +3,7 @@
 import datetime
 import gc
 import sys
+import warnings
 import weakref
 from collections.abc import Iterator
 from math import ceil, modf
@@ -144,18 +145,56 @@ def test_basic_with_auth_colon_in_login() -> None:
 
 
 def test_basic_auth3() -> None:
-    auth = helpers.BasicAuth("nkim")
+    with pytest.warns(DeprecationWarning, match="BasicAuth is deprecated"):
+        auth = helpers.BasicAuth("nkim")
     assert auth.login == "nkim"
     assert auth.password == ""
 
 
 def test_basic_auth4() -> None:
-    auth = helpers.BasicAuth("nkim", "pwd")
+    with pytest.warns(DeprecationWarning, match="BasicAuth is deprecated"):
+        auth = helpers.BasicAuth("nkim", "pwd")
     assert auth.login == "nkim"
     assert auth.password == "pwd"
     assert auth.encode() == "Basic bmtpbTpwd2Q="
 
 
+def test_basic_auth_deprecated() -> None:
+    with pytest.warns(
+        DeprecationWarning,
+        match=(
+            "BasicAuth is deprecated and will be removed in aiohttp 4.0; "
+            "use aiohttp.encode_basic_auth"
+        ),
+    ):
+        helpers.BasicAuth("user", "pass")
+
+
+def test_encode_basic_auth() -> None:
+    assert helpers.encode_basic_auth("nkim", "pwd") == "Basic bmtpbTpwd2Q="
+    assert helpers.encode_basic_auth("") == "Basic Og=="
+    assert (
+        helpers.encode_basic_auth("usér", "pàss", encoding="utf-8")
+        == "Basic dXPDqXI6cMOgc3M="
+    )
+
+
+def test_encode_basic_auth_rejects_colon_in_login() -> None:
+    with pytest.raises(ValueError):
+        helpers.encode_basic_auth("user:1", "pwd")
+
+
+def test_basic_auth_no_warn_helpers_silent() -> None:
+    """Internal aiohttp paths must not raise BasicAuth's deprecation warning."""
+    with warnings.catch_warnings():
+        warnings.simplefilter("error", DeprecationWarning)
+        url = URL("http://user:pass@example.com/")
+        helpers.strip_auth_from_url(url)
+        helpers.BasicAuth.decode("Basic dXNlcjpwYXNz")
+        helpers.BasicAuth.from_url(url)
+        helpers._basic_auth_no_warn("user", "pass")
+
+
 @pytest.mark.parametrize(
     "header",
     (
@@ -199,18 +238,12 @@ def test_basic_auth_decode_invalid_credentials() -> None:
 @pytest.mark.parametrize(
     "credentials, expected_auth",
     (
-        (":", helpers.BasicAuth(login="", password="", encoding="latin1")),
-        (
-            "username:",
-            helpers.BasicAuth(login="username", password="", encoding="latin1"),
-        ),
-        (
-            ":password",
-            helpers.BasicAuth(login="", password="password", encoding="latin1"),
-        ),
+        (":", helpers._basic_auth_no_warn("", "", "latin1")),
+        ("username:", helpers._basic_auth_no_warn("username", "", "latin1")),
+        (":password", helpers._basic_auth_no_warn("", "password", "latin1")),
         (
             "username:password",
-            helpers.BasicAuth(login="username", password="password", encoding="latin1"),
+            helpers._basic_auth_no_warn("username", "password", "latin1"),
         ),
     ),
 )
@@ -1109,15 +1142,15 @@ def test_netrc_from_home_does_not_raise_if_access_denied(
     [
         (
             "machine example.com login username password pass\n",
-            helpers.BasicAuth("username", "pass"),
+            helpers._basic_auth_no_warn("username", "pass", "latin1"),
         ),
         (
             "machine example.com account username password pass\n",
-            helpers.BasicAuth("username", "pass"),
+            helpers._basic_auth_no_warn("username", "pass", "latin1"),
         ),
         (
             "machine example.com password pass\n",
-            helpers.BasicAuth("", "pass"),
+            helpers._basic_auth_no_warn("", "pass", "latin1"),
         ),
     ],
     indirect=("netrc_contents",),
diff --git a/tests/test_proxy.py b/tests/test_proxy.py
index 147b5998b8e..c96bbcf1c3a 100644
--- a/tests/test_proxy.py
+++ b/tests/test_proxy.py
@@ -964,7 +964,7 @@ async def test_proxy_auth_property(
         "GET",
         URL("http://localhost:1234/path"),
         proxy=URL("http://proxy.example.com"),
-        proxy_auth=aiohttp.helpers.BasicAuth("user", "pass"),
+        proxy_auth=aiohttp.helpers._basic_auth_no_warn("user", "pass"),
         loop=event_loop,
     )
     assert ("user", "pass", "latin1") == req.proxy_auth
@@ -1090,7 +1090,7 @@ async def test_https_auth(  # type: ignore[misc]
     proxy_req = ClientRequestBase(
         "GET",
         URL("http://proxy.example.com"),
-        auth=aiohttp.helpers.BasicAuth("user", "pass"),
+        auth=aiohttp.helpers._basic_auth_no_warn("user", "pass"),
         loop=event_loop,
         ssl=True,
         headers=CIMultiDict({}),
diff --git a/tests/test_proxy_functional.py b/tests/test_proxy_functional.py
index 709a8ff9ffa..2df3915f617 100644
--- a/tests/test_proxy_functional.py
+++ b/tests/test_proxy_functional.py
@@ -25,6 +25,16 @@
 
 ASYNCIO_SUPPORTS_TLS_IN_TLS = sys.version_info >= (3, 11)
 
+pytestmark = [
+    pytest.mark.filterwarnings(r"ignore:BasicAuth is deprecated:DeprecationWarning"),
+    pytest.mark.filterwarnings(
+        r"ignore:The 'auth' parameter is deprecated:DeprecationWarning"
+    ),
+    pytest.mark.filterwarnings(
+        r"ignore:The 'proxy_auth' parameter is deprecated:DeprecationWarning"
+    ),
+]
+
 
 class _ResponseArgs(TypedDict):
     status: int