diff --git a/flake/dev/flake.lock b/flake/dev/flake.lock
index 19dc64b0..97e0a72a 100644
--- a/flake/dev/flake.lock
+++ b/flake/dev/flake.lock
@@ -321,7 +321,8 @@
         "nixvim": "nixvim",
         "nvf": "nvf",
         "spicetify-nix": "spicetify-nix",
-        "treefmt-nix": "treefmt-nix"
+        "treefmt-nix": "treefmt-nix",
+        "zen-browser": "zen-browser"
       }
     },
     "spicetify-nix": {
@@ -381,6 +382,29 @@
         "repo": "treefmt-nix",
         "type": "github"
       }
+    },
+    "zen-browser": {
+      "inputs": {
+        "home-manager": [
+          "home-manager"
+        ],
+        "nixpkgs": [
+          "dev-nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1752758254,
+        "narHash": "sha256-VP+f1kJmTsJW+62HtJRZw/luhKHaT06lByAI3/6dXSQ=",
+        "owner": "0xc000022070",
+        "repo": "zen-browser-flake",
+        "rev": "9aa65a267cba3e8334e3af8ec005e75d9c391bbe",
+        "type": "github"
+      },
+      "original": {
+        "owner": "0xc000022070",
+        "repo": "zen-browser-flake",
+        "type": "github"
+      }
     }
   },
   "root": "root",
diff --git a/flake/dev/flake.nix b/flake/dev/flake.nix
index 25c7a948..0f53b2bd 100644
--- a/flake/dev/flake.nix
+++ b/flake/dev/flake.nix
@@ -173,6 +173,14 @@
       url = "github:numtide/treefmt-nix";
       inputs.nixpkgs.follows = "dev-nixpkgs";
     };
+
+    zen-browser = {
+      url = "github:0xc000022070/zen-browser-flake";
+      inputs = {
+        nixpkgs.follows = "dev-nixpkgs";
+        home-manager.follows = "home-manager";
+      };
+    };
     # keep-sorted end
   };
 
diff --git a/modules/zen-browser/hm.nix b/modules/zen-browser/hm.nix
new file mode 100644
index 00000000..2f19e690
--- /dev/null
+++ b/modules/zen-browser/hm.nix
@@ -0,0 +1,72 @@
+{
+  mkTarget,
+  lib,
+  config,
+  options,
+  ...
+}:
+mkTarget {
+  name = "zen-browser";
+  humanName = "Zen Browser";
+
+  extraOptions = {
+    profileNames = lib.mkOption {
+      description = "The Zen Browser profile names to apply styling on.";
+      type = lib.types.listOf lib.types.str;
+
+      default = [ ];
+      example = [ "default" ];
+    };
+  };
+
+  configElements =
+    lib.optionals (builtins.hasAttr "zen-browser" options.programs)
+      [
+        (
+          { cfg }:
+          {
+            warnings =
+              lib.optional (config.programs.zen-browser.enable && cfg.profileNames == [ ])
+                ''stylix: zen-browser: `config.stylix.targets.zen-browser.profileNames` is not set. Declare profile names with 'config.stylix.targets.zen-browser.profileNames = [ "<PROFILE_NAME>" ];'.'';
+          }
+        )
+        (
+          {
+            cfg,
+            fonts,
+          }:
+          {
+            programs.zen-browser.profiles = lib.genAttrs cfg.profileNames (_: {
+              settings = {
+                "font.name.monospace.x-western" = fonts.monospace.name;
+                "font.name.sans-serif.x-western" = fonts.sansSerif.name;
+                "font.name.serif.x-western" = fonts.serif.name;
+              };
+            });
+          }
+        )
+        (
+          {
+            cfg,
+            colors,
+          }:
+          {
+            programs.zen-browser.profiles = lib.genAttrs cfg.profileNames (_: {
+              settings = {
+                "toolkit.legacyUserProfileCustomizations.stylesheets" = true;
+              };
+
+              userChrome = colors {
+                template = ./userChrome.css.mustache;
+                extension = ".css";
+              };
+
+              userContent = colors {
+                template = ./userContent.css.mustache;
+                extension = ".css";
+              };
+            });
+          }
+        )
+      ];
+}
diff --git a/modules/zen-browser/meta.nix b/modules/zen-browser/meta.nix
new file mode 100644
index 00000000..5ca67793
--- /dev/null
+++ b/modules/zen-browser/meta.nix
@@ -0,0 +1,38 @@
+{ lib, ... }:
+{
+  name = "Zen Browser";
+  homepage = "https://zen-browser.app";
+  maintainers = [ lib.maintainers.MrSom3body ];
+  description = ''
+    This module supports the [Zen Browser](https://zen-browser.app).
+
+    > [!IMPORTANT]
+    >
+    > For any theming to be applied, you need to tell this module which
+    > [profiles](https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data)
+    > you're using:
+    >
+    > ```nix
+    > {
+    >   programs.zen-browser = {
+    >     enable = true;
+    >
+    >     profiles = {
+    >       my-profile = {
+    >         # bookmarks, extensions, search engines...
+    >       };
+    >       my-friends-profile = {
+    >         # bookmarks, extensions, search engines...
+    >       };
+    >     };
+    >   };
+    >
+    >   stylix.targets.zen-browser.profileNames = [ "my-profile" "my-friends-profile" ];
+    > }
+    > ```
+    >
+    > This is necessary due to a limitation of the module system: we can either
+    > detect the list of profiles, or change their configuration, but we can't do
+    > both without infinite recursion.
+  '';
+}
diff --git a/modules/zen-browser/testbeds/zen-browser.nix b/modules/zen-browser/testbeds/zen-browser.nix
new file mode 100644
index 00000000..118aedc3
--- /dev/null
+++ b/modules/zen-browser/testbeds/zen-browser.nix
@@ -0,0 +1,22 @@
+{ lib, ... }:
+let
+  profileName = "stylix";
+in
+{
+  stylix.testbed.ui.command.text = "zen";
+
+  home-manager.sharedModules = lib.singleton {
+    programs.zen-browser = {
+      enable = true;
+      profiles.${profileName} = {
+        isDefault = true;
+        settings = {
+          "app.normandy.first_run" = false;
+          "zen.welcome-screen.seen" = true;
+        };
+      };
+    };
+
+    stylix.targets.zen-browser.profileNames = [ profileName ];
+  };
+}
diff --git a/modules/zen-browser/userChrome.css.mustache b/modules/zen-browser/userChrome.css.mustache
new file mode 100644
index 00000000..8b9ab12d
--- /dev/null
+++ b/modules/zen-browser/userChrome.css.mustache
@@ -0,0 +1,126 @@
+:root {
+  --zen-colors-primary: #{{base02-hex}} !important;
+  --zen-primary-color: #{{base0D-hex}} !important;
+  --zen-colors-secondary: #{{base02-hex}} !important;
+  --zen-colors-tertiary: #{{base01-hex}} !important;
+  --zen-colors-border: #{{base0D-hex}} !important;
+  --toolbarbutton-icon-fill: #{{base0D-hex}} !important;
+  --lwt-text-color: #{{base05-hex}} !important;
+  --toolbar-field-color: #{{base05-hex}} !important;
+  --tab-selected-textcolor: #{{base05-hex}} !important;
+  --toolbar-field-focus-color: #{{base05-hex}} !important;
+  --toolbar-color: #{{base05-hex}} !important;
+  --newtab-text-primary-color: #{{base05-hex}} !important;
+  --arrowpanel-color: #{{base05-hex}} !important;
+  --arrowpanel-background: #{{base00-hex}} !important;
+  --sidebar-text-color: #{{base05-hex}} !important;
+  --lwt-sidebar-text-color: #{{base05-hex}} !important;
+  --lwt-sidebar-background-color: #{{base00-hex}} !important;
+  --toolbar-bgcolor: #{{base02-hex}} !important;
+  --newtab-background-color: #{{base00-hex}} !important;
+  --zen-themed-toolbar-bg: #{{base00-hex}} !important;
+  --zen-main-browser-background: #{{base00-hex}} !important;
+  --toolbox-bgcolor-inactive: #{{base01-hex}} !important;
+}
+
+#permissions-granted-icon {
+  color: #{{base05-hex}} !important;
+}
+
+.sidebar-placesTree {
+  background-color: #{{base00-hex}} !important;
+}
+
+#zen-workspaces-button {
+  background-color: #{{base00-hex}} !important;
+}
+
+#TabsToolbar {
+  background-color: #{{base00-hex}} !important;
+}
+
+#urlbar-background {
+  background-color: #{{base02-hex}} !important;
+}
+
+.content-shortcuts {
+  background-color: #{{base00-hex}} !important;
+  border-color: #{{base0D-hex}} !important;
+}
+
+.urlbarView-url {
+  color: #{{base0D-hex}} !important;
+}
+
+#zenEditBookmarkPanelFaviconContainer {
+  background: #{{base00-hex}} !important;
+}
+
+#zen-media-controls-toolbar {
+  & #zen-media-progress-bar {
+    &::-moz-range-track {
+      background: #{{base02-hex}} !important;
+    }
+  }
+}
+
+toolbar .toolbarbutton-1 {
+  &:not([disabled]) {
+    &:is([open], [checked])
+      > :is(
+        .toolbarbutton-icon,
+        .toolbarbutton-text,
+        .toolbarbutton-badge-stack
+      ) {
+      fill: #{{base00-hex}};
+    }
+  }
+}
+
+.identity-color-blue {
+  --identity-tab-color: #{{base0D-hex}} !important;
+  --identity-icon-color: #{{base0D-hex}} !important;
+}
+
+.identity-color-turquoise {
+  --identity-tab-color: #{{base0C-hex}} !important;
+  --identity-icon-color: #{{base0C-hex}} !important;
+}
+
+.identity-color-green {
+  --identity-tab-color: #{{base0B-hex}} !important;
+  --identity-icon-color: #{{base0B-hex}} !important;
+}
+
+.identity-color-yellow {
+  --identity-tab-color: #{{base0A-hex}} !important;
+  --identity-icon-color: #{{base0A-hex}} !important;
+}
+
+.identity-color-orange {
+  --identity-tab-color: #{{base09-hex}} !important;
+  --identity-icon-color: #{{base09-hex}} !important;
+}
+
+.identity-color-red {
+  --identity-tab-color: #{{base08-hex}} !important;
+  --identity-icon-color: #{{base08-hex}} !important;
+}
+
+.identity-color-pink {
+  --identity-tab-color: #{{base0E-hex}} !important;
+  --identity-icon-color: #{{base0E-hex}} !important;
+}
+
+.identity-color-purple {
+  --identity-tab-color: #{{base0F-hex}} !important;
+  --identity-icon-color: #{{base0F-hex}} !important;
+}
+
+hbox#titlebar {
+  background-color: #{{base00-hex}} !important;
+}
+
+#zen-appcontent-navbar-container {
+  background-color: #{{base00-hex}} !important;
+}
diff --git a/modules/zen-browser/userContent.css.mustache b/modules/zen-browser/userContent.css.mustache
new file mode 100644
index 00000000..37c79895
--- /dev/null
+++ b/modules/zen-browser/userContent.css.mustache
@@ -0,0 +1,149 @@
+/* Common variables affecting all pages */
+@-moz-document url-prefix("about:") {
+  :root {
+    --in-content-page-color: #{{base05-hex}} !important;
+    --color-accent-primary: #{{base0D-hex}} !important;
+    --color-accent-primary-hover: #{{base0D-hex}} !important;
+    --color-accent-primary-active: #{{base0D-hex}} !important;
+    background-color: #{{base00-hex}} !important;
+    --in-content-page-background: #{{base00-hex}} !important;
+  }
+}
+
+/* Variables and styles specific to about:newtab and about:home */
+@-moz-document url("about:newtab"), url("about:home") {
+
+  :root {
+    --newtab-background-color: #{{base00-hex}} !important;
+    --newtab-background-color-secondary: #{{base02-hex}} !important;
+    --newtab-element-hover-color: #{{base02-hex}} !important;
+    --newtab-text-primary-color: #{{base05-hex}} !important;
+    --newtab-wordmark-color: #{{base05-hex}} !important;
+    --newtab-primary-action-background: #{{base0D-hex}} !important;
+  }
+
+  .icon {
+    color: #{{base0D-hex}} !important;
+  }
+
+  .search-wrapper .logo-and-wordmark .logo {
+    display: inline-block !important;
+    height: 82px !important;
+    width: 82px !important;
+    background-size: 82px !important;
+  }
+
+  @media (max-width: 609px) {
+    .search-wrapper .logo-and-wordmark .logo {
+      background-size: 64px !important;
+      height: 64px !important;
+      width: 64px !important;
+    }
+  }
+
+  .card-outer:is(:hover, :focus, .active):not(.placeholder) .card-title {
+    color: #{{base0D-hex}} !important;
+  }
+
+  .top-site-outer .search-topsite {
+    background-color: #{{base0D-hex}} !important;
+  }
+
+  .compact-cards .card-outer .card-context .card-context-icon.icon-download {
+    fill: #{{base0B-hex}} !important;
+  }
+}
+
+/* Variables and styles specific to about:preferences */
+@-moz-document url-prefix("about:preferences") {
+  :root {
+    --zen-colors-tertiary: #{{base01-hex}} !important;
+    --in-content-text-color: #{{base05-hex}} !important;
+    --link-color: #{{base0D-hex}} !important;
+    --link-color-hover: #{{base0D-hex}} !important;
+    --zen-colors-primary: #{{base02-hex}} !important;
+    --in-content-box-background: #{{base02-hex}} !important;
+    --zen-primary-color: #{{base0D-hex}} !important;
+  }
+
+  groupbox , moz-card{
+    background: #{{base00-hex}} !important;
+  }
+
+  button,
+  groupbox menulist {
+    background: #{{base02-hex}} !important;
+    color: #{{base05-hex}} !important;
+  }
+
+  .main-content {
+    background-color: #{{base00-hex}} !important;
+  }
+
+  .identity-color-blue {
+    --identity-tab-color: #{{base0D-hex}} !important;
+    --identity-icon-color: #{{base0D-hex}} !important;
+  }
+
+  .identity-color-turquoise {
+    --identity-tab-color: #{{base0C-hex}} !important;
+    --identity-icon-color: #{{base0C-hex}} !important;
+  }
+
+  .identity-color-green {
+    --identity-tab-color: #{{base0B-hex}} !important;
+    --identity-icon-color: #{{base0B-hex}} !important;
+  }
+
+  .identity-color-yellow {
+    --identity-tab-color: #{{base0A-hex}} !important;
+    --identity-icon-color: #{{base0A-hex}} !important;
+  }
+
+  .identity-color-orange {
+    --identity-tab-color: #{{base09-hex}} !important;
+    --identity-icon-color: #{{base09-hex}} !important;
+  }
+
+  .identity-color-red {
+    --identity-tab-color: #{{base08-hex}} !important;
+    --identity-icon-color: #{{base08-hex}} !important;
+  }
+
+  .identity-color-pink {
+    --identity-tab-color: #{{base0E-hex}} !important;
+    --identity-icon-color: #{{base0E-hex}} !important;
+  }
+
+  .identity-color-purple {
+    --identity-tab-color: #{{base0F-hex}} !important;
+    --identity-icon-color: #{{base0F-hex}} !important;
+  }
+
+/* Variables and styles specific to about:addons */
+@-moz-document url-prefix("about:addons") {
+  :root {
+    --zen-dark-color-mix-base: #{{base01-hex}} !important;
+    --background-color-box: #{{base00-hex}} !important;
+  }
+}
+
+/* Variables and styles specific to about:protections */
+@-moz-document url-prefix("about:protections") {
+  :root {
+    --zen-primary-color: #{{base00-hex}} !important;
+    --social-color: #{{base0E-hex}} !important;
+    --coockie-color: #{{base0D-hex}} !important;
+    --fingerprinter-color: #{{base0A-hex}} !important;
+    --cryptominer-color: #{{base0F-hex}} !important;
+    --tracker-color: #{{base0B-hex}} !important;
+    --in-content-primary-button-background-hover: #{{base03-hex}} !important;
+    --in-content-primary-button-text-color-hover: #{{base05-hex}} !important;
+    --in-content-primary-button-background: #{{base03-hex}} !important;
+    --in-content-primary-button-text-color: #{{base05-hex}} !important;
+  }
+
+  .card {
+    background-color: #{{base02-hex}} !important;
+  }
+}
diff --git a/stylix/testbed/default.nix b/stylix/testbed/default.nix
index 982ac67d..da52f7b6 100644
--- a/stylix/testbed/default.nix
+++ b/stylix/testbed/default.nix
@@ -37,6 +37,12 @@ let
                 inherit (inputs.spicetify-nix.nixosModules) spicetify;
 
                 nvf = inputs.nvf.nixosModules.default;
+
+                zen-browser = {
+                  home-manager.sharedModules = [
+                    inputs.zen-browser.homeModules.default
+                  ];
+                };
               };
       };
     in