diff --git a/pkgs/applications/editors/emacs/elisp-packages/manual-packages.nix b/pkgs/applications/editors/emacs/elisp-packages/manual-packages.nix
index 4f2e408fe84a..32210ac7497e 100644
--- a/pkgs/applications/editors/emacs/elisp-packages/manual-packages.nix
+++ b/pkgs/applications/editors/emacs/elisp-packages/manual-packages.nix
@@ -47,9 +47,6 @@ lib.packagesFromDirectoryRecursive {
 
   zstd = callPackage ./manual-packages/zstd { inherit (pkgs) zstd; };
 
-  # From old emacsPackages (pre emacsPackagesNg)
-  cedille = callPackage ./manual-packages/cedille { inherit (pkgs) cedille; };
-
   # camelCase aliases for some of the kebab-case expressions above
   colorThemeSolarized = self.color-theme-solarized;
   emacsSessionManagement = self.session-management-for-emacs;
diff --git a/pkgs/applications/editors/emacs/elisp-packages/manual-packages/cedille/default.nix b/pkgs/applications/editors/emacs/elisp-packages/manual-packages/cedille/default.nix
deleted file mode 100644
index cb514eef5347..000000000000
--- a/pkgs/applications/editors/emacs/elisp-packages/manual-packages/cedille/default.nix
+++ /dev/null
@@ -1,38 +0,0 @@
-{
-  stdenv,
-  cedille,
-  emacs,
-}:
-
-stdenv.mkDerivation {
-  pname = "cedille-mode";
-
-  inherit (cedille) version src;
-
-  buildInputs = [ emacs ];
-
-  dontBuild = true;
-
-  installPhase = ''
-    runHook preInstall
-
-    install -d $out/share/emacs/site-lisp
-    install se-mode/*.el se-mode/*.elc $out/share/emacs/site-lisp
-    install cedille-mode/*.el cedille-mode/*.elc $out/share/emacs/site-lisp
-    install *.el *.elc $out/share/emacs/site-lisp
-    substituteInPlace $out/share/emacs/site-lisp/cedille-mode.el \
-      --replace /usr/bin/cedille ${cedille}/bin/cedille
-
-    runHook postInstall
-  '';
-
-  meta = {
-    inherit (cedille.meta)
-      homepage
-      license
-      maintainers
-      platforms
-      ;
-    description = "Emacs major mode for Cedille";
-  };
-}
diff --git a/pkgs/applications/science/logic/cedille/Fix-to-string.agda-to-compile-with-Agda-2.6.1.patch b/pkgs/applications/science/logic/cedille/Fix-to-string.agda-to-compile-with-Agda-2.6.1.patch
deleted file mode 100644
index 51f1478987eb..000000000000
--- a/pkgs/applications/science/logic/cedille/Fix-to-string.agda-to-compile-with-Agda-2.6.1.patch
+++ /dev/null
@@ -1,31 +0,0 @@
-From 563f023aba1034f4f433f412302b825b059ef5a5 Mon Sep 17 00:00:00 2001
-From: Mark Barbone <mark.l.barbone@gmail.com>
-Date: Sun, 19 Jul 2020 17:24:30 -0400
-Subject: [PATCH] Fix to-string.agda to compile with Agda 2.6.1
-
----
-Adapted from https://github.com/cedille/cedille/pull/156.
-
- src/to-string.agda | 6 +++---
- 1 file changed, 3 insertions(+), 3 deletions(-)
-
-diff --git a/src/to-string.agda b/src/to-string.agda
-index 2505942..051a2da 100644
---- a/src/to-string.agda
-+++ b/src/to-string.agda
-@@ -100,9 +100,9 @@ no-parens {TK} _ _ _ = tt
- no-parens {QUALIF} _ _ _ = tt
- no-parens {ARG} _ _ _ = tt
- 
--pattern ced-ops-drop-spine = cedille-options.options.mk-options _ _ _ _ ff _ _ _ ff _
--pattern ced-ops-conv-arr = cedille-options.options.mk-options _ _ _ _ _ _ _ _ ff _
--pattern ced-ops-conv-abs = cedille-options.options.mk-options _ _ _ _ _ _ _ _ tt _
-+pattern ced-ops-drop-spine = cedille-options.mk-options _ _ _ _ ff _ _ _ ff _
-+pattern ced-ops-conv-arr = cedille-options.mk-options _ _ _ _ _ _ _ _ ff _
-+pattern ced-ops-conv-abs = cedille-options.mk-options _ _ _ _ _ _ _ _ tt _
- 
- drop-spine : cedille-options.options → {ed : exprd} → ctxt → ⟦ ed ⟧ → ⟦ ed ⟧
- drop-spine ops @ ced-ops-drop-spine = h
--- 
-2.27.0
-
diff --git a/pkgs/applications/science/logic/cedille/default.nix b/pkgs/applications/science/logic/cedille/default.nix
deleted file mode 100644
index d5a9c617efb8..000000000000
--- a/pkgs/applications/science/logic/cedille/default.nix
+++ /dev/null
@@ -1,67 +0,0 @@
-{
-  stdenv,
-  lib,
-  fetchFromGitHub,
-  alex,
-  happy,
-  Agda,
-  buildPackages,
-  ghcWithPackages,
-}:
-
-stdenv.mkDerivation rec {
-  version = "1.1.2";
-  pname = "cedille";
-
-  src = fetchFromGitHub {
-    owner = "cedille";
-    repo = "cedille";
-    rev = "v${version}";
-    sha256 = "1j745q9sd32fhcb96wjq6xvyqq1k6imppjnya6x0n99fyfnqzvg9";
-    fetchSubmodules = true;
-  };
-
-  patches = [
-    ./Fix-to-string.agda-to-compile-with-Agda-2.6.1.patch
-  ];
-
-  nativeBuildInputs = [
-    alex
-    happy
-  ];
-  buildInputs = [
-    Agda
-    (ghcWithPackages (ps: [ ps.ieee ]))
-  ];
-
-  LANG = "en_US.UTF-8";
-  LOCALE_ARCHIVE = lib.optionalString (
-    stdenv.buildPlatform.libc == "glibc"
-  ) "${buildPackages.glibcLocales}/lib/locale/locale-archive";
-
-  postPatch = ''
-    patchShebangs create-libraries.sh
-  '';
-
-  installPhase = ''
-    install -Dm755 -t $out/bin/ cedille
-    install -Dm755 -t $out/bin/ core/cedille-core
-    install -Dm644 -t $out/share/info docs/info/cedille-info-main.info
-
-    mkdir -p $out/lib/
-    cp -r lib/ $out/lib/cedille/
-  '';
-
-  meta = {
-    description = "Interactive theorem-prover and dependently typed programming language, based on extrinsic (aka Curry-style) type theory";
-    homepage = "https://cedille.github.io/";
-    license = lib.licenses.mit;
-    maintainers = with lib.maintainers; [ mpickering ];
-    platforms = lib.platforms.unix;
-
-    # Broken due to Agda update.  See
-    # https://github.com/NixOS/nixpkgs/pull/129606#issuecomment-881107449.
-    broken = true;
-    hydraPlatforms = lib.platforms.none;
-  };
-}
diff --git a/pkgs/top-level/aliases.nix b/pkgs/top-level/aliases.nix
index 7add2b9a2993..4fe5cd7a7cc0 100644
--- a/pkgs/top-level/aliases.nix
+++ b/pkgs/top-level/aliases.nix
@@ -415,6 +415,7 @@ mapAliases {
   catch = throw "catch has been removed. Please upgrade to catch2 or catch2_3"; # Added 2025-08-21
   catnip-gtk4 = throw "'catnip-gtk4' has been removed, as it has been unmaintained upstream since June 2023, use cavasik or cavalier instead"; # Added 2026-01-01
   cdwe = throw "'cdwe' has been removed, as it has been unmaintained upstream since June 2023"; # Added 2026-01-01
+  cedille = throw "'cedille' has been removed due to being broken for more than a year; see RFC 180"; # Added 2026-02-05
   cereal_1_3_0 = throw "cereal_1_3_0 has been removed as it was unused; use cereal intsead"; # Added 2025-09-12
   cereal_1_3_2 = throw "cereal_1_3_2 is now the only version and has been renamed to cereal"; # Added 2025-09-12
   certmgr-selfsigned = throw "'certmgr-selfsigned' has been renamed to/replaced by 'certmgr'"; # Converted to throw 2025-10-27
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index ffe5a114f6e8..b4d6b2df0510 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -1622,15 +1622,6 @@ with pkgs;
       '';
     });
 
-  cedille = callPackage ../applications/science/logic/cedille {
-    inherit (haskellPackages)
-      alex
-      happy
-      Agda
-      ghcWithPackages
-      ;
-  };
-
   clevercsv = with python3Packages; toPythonApplication clevercsv;
 
   cleanit = with python3Packages; toPythonApplication cleanit;