diff --git a/pkgs/top-level/aliases.nix b/pkgs/top-level/aliases.nix
index 1911c58b7e7c0..1e7c65304c240 100644
--- a/pkgs/top-level/aliases.nix
+++ b/pkgs/top-level/aliases.nix
@@ -1857,6 +1857,16 @@ mapAliases {
   nix-simple-deploy = throw "'nix-simple-deploy' has been removed as it is broken and unmaintained"; # Added 2024-08-17
   nix-universal-prefetch = throw "The nix-universal-prefetch package was dropped since it was unmaintained."; # Added 2024-06-21
   nixFlakes = throw "'nixFlakes' has been renamed to/replaced by 'nixVersions.stable'"; # Converted to throw 2024-10-17
+  nixfmt-classic =
+    (
+      if lib.oldestSupportedReleaseIsAtLeast 2605 then
+        throw "nixfmt-classic has been removed as it is deprecated and unmaintained."
+      else if lib.oldestSupportedReleaseIsAtLeast 2511 then
+        lib.warnOnInstantiate "nixfmt-classic is deprecated and unmaintained. We recommend switching to nixfmt."
+      else
+        lib.id
+    )
+      haskellPackages.nixfmt.bin;
   nixStable = nixVersions.stable; # Added 2022-01-24
   nixUnstable = throw "nixUnstable has been removed. For bleeding edge (Nix master, roughly weekly updated) use nixVersions.git, otherwise use nixVersions.latest."; # Converted to throw 2024-04-22
   nix_2_3 = throw "'nix_2_3' has been removed, because it was unmaintained and insecure."; # Converted to throw 2025-07-24
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index e39009dfeb3a8..bd62aec71f9b9 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -14840,8 +14840,6 @@ with pkgs;
 
   nix-visualize = python3.pkgs.callPackage ../tools/package-management/nix-visualize { };
 
-  nixfmt-classic = haskellPackages.nixfmt.bin;
-
   nixpkgs-manual = callPackage ../../doc/doc-support/package.nix { };
 
   nixos-artwork = callPackage ../data/misc/nixos-artwork { };