diff --git a/Misc/NEWS.d/next/Windows/2021-11-08-21-53-11.bpo-45732.idl5kx.rst b/Misc/NEWS.d/next/Windows/2021-11-08-21-53-11.bpo-45732.idl5kx.rst
new file mode 100644
index 00000000000000..563bcd33a401a5
--- /dev/null
+++ b/Misc/NEWS.d/next/Windows/2021-11-08-21-53-11.bpo-45732.idl5kx.rst
@@ -0,0 +1 @@
+Updates bundled Tcl/Tk to 8.6.12.
diff --git a/PCbuild/get_externals.bat b/PCbuild/get_externals.bat
index 484543d5999b83..207f91baba5371 100644
--- a/PCbuild/get_externals.bat
+++ b/PCbuild/get_externals.bat
@@ -55,8 +55,8 @@ set libraries=%libraries%                                       bzip2-1.0.6
 if NOT "%IncludeLibffiSrc%"=="false" set libraries=%libraries%  libffi-3.4.2
 if NOT "%IncludeSSLSrc%"=="false" set libraries=%libraries%     openssl-1.1.1l
 set libraries=%libraries%                                       sqlite-3.36.0.0
-if NOT "%IncludeTkinterSrc%"=="false" set libraries=%libraries% tcl-core-8.6.11.1
-if NOT "%IncludeTkinterSrc%"=="false" set libraries=%libraries% tk-8.6.11.1
+if NOT "%IncludeTkinterSrc%"=="false" set libraries=%libraries% tcl-core-8.6.12.0
+if NOT "%IncludeTkinterSrc%"=="false" set libraries=%libraries% tk-8.6.12.0
 if NOT "%IncludeTkinterSrc%"=="false" set libraries=%libraries% tix-8.4.3.6
 set libraries=%libraries%                                       xz-5.2.2
 set libraries=%libraries%                                       zlib-1.2.11
@@ -78,7 +78,7 @@ echo.Fetching external binaries...
 set binaries=
 if NOT "%IncludeLibffi%"=="false"  set binaries=%binaries% libffi-3.4.2
 if NOT "%IncludeSSL%"=="false"     set binaries=%binaries% openssl-bin-1.1.1l
-if NOT "%IncludeTkinter%"=="false" set binaries=%binaries% tcltk-8.6.11.1
+if NOT "%IncludeTkinter%"=="false" set binaries=%binaries% tcltk-8.6.12.0
 if NOT "%IncludeSSLSrc%"=="false"  set binaries=%binaries% nasm-2.11.06
 
 for %%b in (%binaries%) do (
diff --git a/PCbuild/tcltk.props b/PCbuild/tcltk.props
index 228efb34d73999..16dc35d45ebd5c 100644
--- a/PCbuild/tcltk.props
+++ b/PCbuild/tcltk.props
@@ -4,8 +4,8 @@
   <PropertyGroup>
     <TclMajorVersion>8</TclMajorVersion>
     <TclMinorVersion>6</TclMinorVersion>
-    <TclPatchLevel>11</TclPatchLevel>
-    <TclRevision>1</TclRevision>
+    <TclPatchLevel>12</TclPatchLevel>
+    <TclRevision>0</TclRevision>
     <TkMajorVersion>$(TclMajorVersion)</TkMajorVersion>
     <TkMinorVersion>$(TclMinorVersion)</TkMinorVersion>
     <TkPatchLevel>$(TclPatchLevel)</TkPatchLevel>