diff --git a/stubs/requests/requests/api.pyi b/stubs/requests/requests/api.pyi
index ee6f446e5ca5..0006f6851bfa 100644
--- a/stubs/requests/requests/api.pyi
+++ b/stubs/requests/requests/api.pyi
@@ -1,7 +1,19 @@
 from typing import Any
 
 from .models import Response
-from .sessions import RequestsCookieJar, _Auth, _Cert, _Data, _Files, _HooksInput, _Params, _TextMapping, _Timeout, _Verify
+from .sessions import (
+    RequestsCookieJar,
+    _Auth,
+    _Cert,
+    _Data,
+    _Files,
+    _HeadersMapping,
+    _HooksInput,
+    _Params,
+    _TextMapping,
+    _Timeout,
+    _Verify,
+)
 
 def request(
     method: str | bytes,
@@ -9,7 +21,7 @@ def request(
     *,
     params: _Params | None = ...,
     data: _Data | None = ...,
-    headers: _TextMapping | None = ...,
+    headers: _HeadersMapping | None = ...,
     cookies: RequestsCookieJar | _TextMapping | None = ...,
     files: _Files | None = ...,
     auth: _Auth | None = ...,
@@ -27,7 +39,7 @@ def get(
     params: _Params | None = ...,
     *,
     data: _Data | None = ...,
-    headers: _TextMapping | None = ...,
+    headers: _HeadersMapping | None = ...,
     cookies: RequestsCookieJar | _TextMapping | None = ...,
     files: _Files | None = ...,
     auth: _Auth | None = ...,
@@ -45,7 +57,7 @@ def options(
     *,
     params: _Params | None = ...,
     data: _Data | None = ...,
-    headers: _TextMapping | None = ...,
+    headers: _HeadersMapping | None = ...,
     cookies: RequestsCookieJar | _TextMapping | None = ...,
     files: _Files | None = ...,
     auth: _Auth | None = ...,
@@ -63,7 +75,7 @@ def head(
     *,
     params: _Params | None = ...,
     data: _Data | None = ...,
-    headers: _TextMapping | None = ...,
+    headers: _HeadersMapping | None = ...,
     cookies: RequestsCookieJar | _TextMapping | None = ...,
     files: _Files | None = ...,
     auth: _Auth | None = ...,
@@ -82,7 +94,7 @@ def post(
     json: Any | None = ...,
     *,
     params: _Params | None = ...,
-    headers: _TextMapping | None = ...,
+    headers: _HeadersMapping | None = ...,
     cookies: RequestsCookieJar | _TextMapping | None = ...,
     files: _Files | None = ...,
     auth: _Auth | None = ...,
@@ -99,7 +111,7 @@ def put(
     data: _Data | None = ...,
     *,
     params: _Params | None = ...,
-    headers: _TextMapping | None = ...,
+    headers: _HeadersMapping | None = ...,
     cookies: RequestsCookieJar | _TextMapping | None = ...,
     files: _Files | None = ...,
     auth: _Auth | None = ...,
@@ -117,7 +129,7 @@ def patch(
     data: _Data | None = ...,
     *,
     params: _Params | None = ...,
-    headers: _TextMapping | None = ...,
+    headers: _HeadersMapping | None = ...,
     cookies: RequestsCookieJar | _TextMapping | None = ...,
     files: _Files | None = ...,
     auth: _Auth | None = ...,
@@ -135,7 +147,7 @@ def delete(
     *,
     params: _Params | None = ...,
     data: _Data | None = ...,
-    headers: _TextMapping | None = ...,
+    headers: _HeadersMapping | None = ...,
     cookies: RequestsCookieJar | _TextMapping | None = ...,
     files: _Files | None = ...,
     auth: _Auth | None = ...,
diff --git a/stubs/requests/requests/sessions.pyi b/stubs/requests/requests/sessions.pyi
index a0143f60e3d6..49c69d3da6a6 100644
--- a/stubs/requests/requests/sessions.pyi
+++ b/stubs/requests/requests/sessions.pyi
@@ -67,12 +67,22 @@ _Params: TypeAlias = Union[
     str | bytes,
 ]
 _TextMapping: TypeAlias = MutableMapping[str, str]
+_HeadersMapping: TypeAlias = MutableMapping[str, str] | MutableMapping[str, bytes] | MutableMapping[str, str | bytes]
+_HeadersUpdateMapping: TypeAlias = (
+    MutableMapping[str, str]
+    | MutableMapping[str, bytes]
+    | MutableMapping[str, None]
+    | MutableMapping[str, str | bytes]
+    | MutableMapping[str, str | None]
+    | MutableMapping[str, bytes | None]
+    | MutableMapping[str, str | bytes | None]
+)
 _Timeout: TypeAlias = Union[float, tuple[float, float], tuple[float, None]]
 _Verify: TypeAlias = bool | str
 
 class Session(SessionRedirectMixin):
     __attrs__: Any
-    headers: CaseInsensitiveDict[str]
+    headers: CaseInsensitiveDict[str | bytes]
     auth: _Auth | None
     proxies: _TextMapping
     hooks: _Hooks
@@ -95,7 +105,7 @@ class Session(SessionRedirectMixin):
         url: str | bytes,
         params: _Params | None = ...,
         data: _Data | None = ...,
-        headers: _TextMapping | None = ...,
+        headers: _HeadersUpdateMapping | None = ...,
         cookies: None | RequestsCookieJar | _TextMapping = ...,
         files: _Files | None = ...,
         auth: _Auth | None = ...,
@@ -114,7 +124,7 @@ class Session(SessionRedirectMixin):
         *,
         params: _Params | None = ...,
         data: _Data | None = ...,
-        headers: _TextMapping | None = ...,
+        headers: _HeadersUpdateMapping | None = ...,
         cookies: RequestsCookieJar | _TextMapping | None = ...,
         files: _Files | None = ...,
         auth: _Auth | None = ...,
@@ -133,7 +143,7 @@ class Session(SessionRedirectMixin):
         *,
         params: _Params | None = ...,
         data: _Data | None = ...,
-        headers: _TextMapping | None = ...,
+        headers: _HeadersUpdateMapping | None = ...,
         cookies: RequestsCookieJar | _TextMapping | None = ...,
         files: _Files | None = ...,
         auth: _Auth | None = ...,
@@ -152,7 +162,7 @@ class Session(SessionRedirectMixin):
         *,
         params: _Params | None = ...,
         data: _Data | None = ...,
-        headers: _TextMapping | None = ...,
+        headers: _HeadersUpdateMapping | None = ...,
         cookies: RequestsCookieJar | _TextMapping | None = ...,
         files: _Files | None = ...,
         auth: _Auth | None = ...,
@@ -172,7 +182,7 @@ class Session(SessionRedirectMixin):
         json: Any | None = ...,
         *,
         params: _Params | None = ...,
-        headers: _TextMapping | None = ...,
+        headers: _HeadersUpdateMapping | None = ...,
         cookies: RequestsCookieJar | _TextMapping | None = ...,
         files: _Files | None = ...,
         auth: _Auth | None = ...,
@@ -190,7 +200,7 @@ class Session(SessionRedirectMixin):
         data: _Data | None = ...,
         *,
         params: _Params | None = ...,
-        headers: _TextMapping | None = ...,
+        headers: _HeadersUpdateMapping | None = ...,
         cookies: RequestsCookieJar | _TextMapping | None = ...,
         files: _Files | None = ...,
         auth: _Auth | None = ...,
@@ -209,7 +219,7 @@ class Session(SessionRedirectMixin):
         data: _Data | None = ...,
         *,
         params: _Params | None = ...,
-        headers: _TextMapping | None = ...,
+        headers: _HeadersUpdateMapping | None = ...,
         cookies: RequestsCookieJar | _TextMapping | None = ...,
         files: _Files | None = ...,
         auth: _Auth | None = ...,
@@ -228,7 +238,7 @@ class Session(SessionRedirectMixin):
         *,
         params: _Params | None = ...,
         data: _Data | None = ...,
-        headers: _TextMapping | None = ...,
+        headers: _HeadersUpdateMapping | None = ...,
         cookies: RequestsCookieJar | _TextMapping | None = ...,
         files: _Files | None = ...,
         auth: _Auth | None = ...,