diff --git a/nixos/tests/haproxy.nix b/nixos/tests/haproxy.nix
index bd8b9b288a22..4b7f26765752 100644
--- a/nixos/tests/haproxy.nix
+++ b/nixos/tests/haproxy.nix
@@ -68,7 +68,7 @@
     client =
       { pkgs, ... }:
       {
-        environment.systemPackages = [ pkgs.curlHTTP3 ];
+        environment.systemPackages = [ pkgs.curl ];
       };
   };
   testScript = ''
diff --git a/nixos/tests/nginx-http3.nix b/nixos/tests/nginx-http3.nix
index 1c0326d0f0f6..cd321d43d2e1 100644
--- a/nixos/tests/nginx-http3.nix
+++ b/nixos/tests/nginx-http3.nix
@@ -66,7 +66,7 @@ builtins.listToAttrs (
           client =
             { pkgs, ... }:
             {
-              environment.systemPackages = [ pkgs.curlHTTP3 ];
+              environment.systemPackages = [ pkgs.curl ];
               networking = {
                 interfaces.eth1 = {
                   ipv4.addresses = [
diff --git a/nixos/tests/rustls-libssl.nix b/nixos/tests/rustls-libssl.nix
index 165edb76a5d4..da1c15c8cb27 100644
--- a/nixos/tests/rustls-libssl.nix
+++ b/nixos/tests/rustls-libssl.nix
@@ -64,7 +64,7 @@ in
     client =
       { pkgs, ... }:
       {
-        environment.systemPackages = [ pkgs.curlHTTP3 ];
+        environment.systemPackages = [ pkgs.curl ];
         networking = {
           interfaces.eth1 = {
             ipv4.addresses = [
diff --git a/nixos/tests/sing-box.nix b/nixos/tests/sing-box.nix
index 0825684e0bed..239114924537 100644
--- a/nixos/tests/sing-box.nix
+++ b/nixos/tests/sing-box.nix
@@ -249,7 +249,7 @@ in
         ];
 
         environment.systemPackages = [
-          pkgs.curlHTTP3
+          pkgs.curl
           pkgs.iproute2
         ];
 
@@ -308,7 +308,7 @@ in
         ];
 
         environment.systemPackages = [
-          pkgs.curlHTTP3
+          pkgs.curl
           pkgs.iproute2
         ];
 
@@ -369,7 +369,7 @@ in
           (builtins.readFile ./common/acme/server/ca.cert.pem)
         ];
 
-        environment.systemPackages = [ pkgs.curlHTTP3 ];
+        environment.systemPackages = [ pkgs.curl ];
 
         systemd.services.sing-box.serviceConfig.ExecStartPost = [
           "+${tproxyPost}/bin/exe"
diff --git a/nixos/tests/web-servers/h2o/basic.nix b/nixos/tests/web-servers/h2o/basic.nix
index 52a4b58429e8..622bb96929bf 100644
--- a/nixos/tests/web-servers/h2o/basic.nix
+++ b/nixos/tests/web-servers/h2o/basic.nix
@@ -44,7 +44,7 @@ in
       { pkgs, ... }:
       {
         environment.systemPackages = [
-          pkgs.curlHTTP3
+          pkgs.curl
         ];
 
         services.h2o = {
diff --git a/pkgs/by-name/ht/https-dns-proxy/package.nix b/pkgs/by-name/ht/https-dns-proxy/package.nix
index a37168689b58..31a4462f349e 100644
--- a/pkgs/by-name/ht/https-dns-proxy/package.nix
+++ b/pkgs/by-name/ht/https-dns-proxy/package.nix
@@ -5,13 +5,10 @@
   cmake,
   gtest,
   c-ares,
-  curlHTTP3,
+  curl,
   libev,
 }:
 
-let
-  curl' = curlHTTP3;
-in
 stdenv.mkDerivation rec {
   pname = "https-dns-proxy";
   # there are no stable releases (yet?)
@@ -38,7 +35,7 @@ stdenv.mkDerivation rec {
 
   buildInputs = [
     c-ares
-    curl'
+    curl
     libev
   ];
 
diff --git a/pkgs/by-name/ng/nghttp3/package.nix b/pkgs/by-name/ng/nghttp3/package.nix
index a6e1497d70ed..784e5c3ecf6a 100644
--- a/pkgs/by-name/ng/nghttp3/package.nix
+++ b/pkgs/by-name/ng/nghttp3/package.nix
@@ -3,7 +3,7 @@
   stdenv,
   fetchurl,
   cmake,
-  curlHTTP3,
+  curl,
 }:
 
 stdenv.mkDerivation (finalAttrs: {
@@ -30,7 +30,7 @@ stdenv.mkDerivation (finalAttrs: {
   doCheck = true;
 
   passthru.tests = {
-    inherit curlHTTP3;
+    inherit curl;
   };
 
   meta = {
diff --git a/pkgs/development/libraries/ngtcp2/default.nix b/pkgs/development/libraries/ngtcp2/default.nix
index 916d9d5d770c..bf595f473050 100644
--- a/pkgs/development/libraries/ngtcp2/default.nix
+++ b/pkgs/development/libraries/ngtcp2/default.nix
@@ -9,7 +9,7 @@
   openssl,
   withJemalloc ? false,
   jemalloc,
-  curlHTTP3,
+  curl,
 }:
 
 stdenv.mkDerivation (finalAttrs: {
@@ -43,7 +43,7 @@ stdenv.mkDerivation (finalAttrs: {
   doCheck = true;
 
   passthru.tests = {
-    inherit curlHTTP3;
+    inherit curl;
   };
 
   meta = {
diff --git a/pkgs/top-level/aliases.nix b/pkgs/top-level/aliases.nix
index b991514bb974..918029d559ee 100644
--- a/pkgs/top-level/aliases.nix
+++ b/pkgs/top-level/aliases.nix
@@ -694,6 +694,7 @@ mapAliases {
   cudaPackages_12_4 = throw "CUDA 12.4 has been removed from Nixpkgs, as it is unmaintained upstream and depends on unsupported compilers"; # Added 2025-08-08
   cudaPackages_12_5 = throw "CUDA 12.5 has been removed from Nixpkgs, as it is unmaintained upstream and depends on unsupported compilers"; # Added 2025-08-08
   cups-kyodialog3 = cups-kyodialog; # Added 2022-11-12
+  curlHTTP3 = lib.warnOnInstantiate "'curlHTTP3' has been removed, as 'curl' now has HTTP/3 support enabled by default" curl; # Added 2025-08-22
   cutemarked-ng = throw "'cutemarked-ng' has been removed due to lack of maintenance upstream. Consider using 'kdePackages.ghostwriter' instead"; # Added 2024-12-27
   cvs_fast_export = throw "'cvs_fast_export' has been renamed to/replaced by 'cvs-fast-export'"; # Converted to throw 2024-10-17
   cyber = throw "cyber has been removed, as it does not build with supported Zig versions"; # Added 2025-08-09
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 45583ebd46e2..f689f5196922 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -2643,10 +2643,6 @@ with pkgs;
     websocketSupport = true;
   };
 
-  curlHTTP3 = curl.override {
-    http3Support = true;
-  };
-
   curl = curlMinimal.override (
     {
       idnSupport = true;