diff --git a/lib/default.nix b/lib/default.nix
index aff1df150f13..3fda156b75a9 100644
--- a/lib/default.nix
+++ b/lib/default.nix
@@ -152,7 +152,7 @@ let
       scrubOptionValue literalExpression literalExample
       showOption showOptionWithDefLocs showFiles
       unknownModule mkOption mkPackageOption mkPackageOptionMD
-      mdDoc literalMD;
+      literalMD;
     inherit (self.types) isType setType defaultTypeMerge defaultFunctor
       isOptionType mkOptionType;
     inherit (self.asserts)
diff --git a/lib/options.nix b/lib/options.nix
index f4d0d9d36cfc..4f75da5ad51a 100644
--- a/lib/options.nix
+++ b/lib/options.nix
@@ -399,13 +399,6 @@ rec {
 
   literalExample = lib.warn "lib.literalExample is deprecated, use lib.literalExpression instead, or use lib.literalMD for a non-Nix description." literalExpression;
 
-  /* Transition marker for documentation that's already migrated to markdown
-     syntax. Has been a no-op for some while and been removed from nixpkgs.
-     Kept here to alert downstream users who may not be aware of the migration's
-     completion that it should be removed from modules.
-  */
-  mdDoc = lib.warn "lib.mdDoc will be removed from nixpkgs in 24.11. Option descriptions are now in Markdown by default; you can remove any remaining uses of lib.mdDoc.";
-
   /* For use in the `defaultText` and `example` option attributes. Causes the
      given MD text to be inserted verbatim in the documentation, for when
      a `literalExpression` would be too hard to read.
diff --git a/nixos/lib/make-options-doc/default.nix b/nixos/lib/make-options-doc/default.nix
index 210fbd1a0e99..84b965b149e3 100644
--- a/nixos/lib/make-options-doc/default.nix
+++ b/nixos/lib/make-options-doc/default.nix
@@ -111,18 +111,8 @@
 # instead of printing warnings for eg options with missing descriptions (which may be lost
 # by nix build unless -L is given), emit errors instead and fail the build
 , warningsAreErrors ? true
-# allow docbook option docs if `true`. only markdown documentation is allowed when set to
-# `false`, and a different renderer may be used with different bugs and performance
-# characteristics but (hopefully) indistinguishable output.
-# deprecated since 23.11.
-# TODO remove in a while.
-, allowDocBook ? false
-# TODO remove in a while (see https://github.com/NixOS/nixpkgs/issues/300735)
-, markdownByDefault ? true
 }:
 
-assert markdownByDefault && ! allowDocBook;
-
 let
   rawOpts = lib.optionAttrSetToDocList options;
   transformedOpts = map transformOptions rawOpts;