diff --git a/modules/misc/news/2025/11/2025-11-08_10-23-44.nix b/modules/misc/news/2025/11/2025-11-08_10-23-44.nix
new file mode 100644
index 000000000..a02d19348
--- /dev/null
+++ b/modules/misc/news/2025/11/2025-11-08_10-23-44.nix
@@ -0,0 +1,8 @@
+{ config, ... }:
+{
+  time = "2025-11-08T15:23:44+00:00";
+  condition = config.programs.vicinae.themes != { };
+  message = ''
+    Vicinae theme definitions have been updated to a new format. See https://docs.vicinae.com/theming/getting-started for the new structure.
+  '';
+}
diff --git a/modules/programs/vicinae.nix b/modules/programs/vicinae.nix
index 726c68a08..0267f4fb0 100644
--- a/modules/programs/vicinae.nix
+++ b/modules/programs/vicinae.nix
@@ -8,6 +8,10 @@ let
   cfg = config.programs.vicinae;
 
   jsonFormat = pkgs.formats.json { };
+  tomlFormat = pkgs.formats.toml { };
+
+  packageVersion = if cfg.package != null then lib.getVersion cfg.package else null;
+  themeIsToml = lib.versionAtLeast packageVersion "0.15.0";
 in
 {
   meta.maintainers = [ lib.maintainers.leiserfg ];
@@ -73,35 +77,47 @@ in
     };
 
     themes = lib.mkOption {
-      inherit (jsonFormat) type;
+      inherit (tomlFormat) type;
       default = { };
       description = ''
-        Theme settings to add to the themes folder in `~/.config/vicinae/themes`.
+        Theme settings to add to the themes folder in `~/.config/vicinae/themes`. See <https://docs.vicinae.com/theming/getting-started> for supported values.
 
-        The attribute name of the theme will be the name of theme json file,
-        e.g. `base16-default-dark` will be `base16-default-dark.json`.
+        The attribute name of the theme will be the name of theme file,
+        e.g. `base16-default-dark` will be `base16-default-dark.toml` (or `.json` if vicinae version is < 0.15.0).
       '';
       example =
         lib.literalExpression # nix
           ''
+            # vicinae >= 0.15.0
             {
-              base16-default-dark = {
-                version = "1.0.0";
-                appearance = "dark";
-                icon = /path/to/icon.png;
-                name = "base16 default dark";
-                description = "base16 default dark by Chris Kempson";
-                palette = {
-                  background = "#181818";
-                  foreground = "#d8d8d8";
-                  blue = "#7cafc2";
-                  green = "#a3be8c";
-                  magenta = "#ba8baf";
-                  orange = "#dc9656";
-                  purple = "#a16946";
-                  red = "#ab4642";
-                  yellow = "#f7ca88";
-                  cyan = "#86c1b9";
+              catppuccin-mocha = {
+                meta = {
+                  version = 1;
+                  name = "Catppuccin Mocha";
+                  description = "Cozy feeling with color-rich accents";
+                  variant = "dark";
+                  icon = "icons/catppuccin-mocha.png";
+                  inherits = "vicinae-dark";
+                };
+
+                colors = {
+                  core = {
+                    background = "#1E1E2E";
+                    foreground = "#CDD6F4";
+                    secondary_background = "#181825";
+                    border = "#313244";
+                    accent = "#89B4FA";
+                  };
+                  accents = {
+                    blue = "#89B4FA";
+                    green = "#A6E3A1";
+                    magenta = "#F5C2E7";
+                    orange = "#FAB387";
+                    purple = "#CBA6F7";
+                    red = "#F38BA8";
+                    yellow = "#F9E2AF";
+                    cyan = "#94E2D5";
+                  };
                 };
               };
             }
@@ -197,26 +213,34 @@ in
 
     home.packages = lib.mkIf (cfg.package != null) [ cfg.package ];
 
-    xdg = {
-      configFile = {
-        "vicinae/vicinae.json" = lib.mkIf (cfg.settings != { }) {
-          source = jsonFormat.generate "vicinae-settings" cfg.settings;
-        };
-      }
-      // lib.mapAttrs' (
-        name: theme:
-        lib.nameValuePair "vicinae/themes/${name}.json" {
-          source = jsonFormat.generate "vicinae-${name}-theme" theme;
+    xdg =
+      let
+        themeFormat = if themeIsToml then tomlFormat else jsonFormat;
+        themeExtension = if themeIsToml then "toml" else "json";
+        themeFiles = lib.mapAttrs' (
+          name: theme:
+          lib.nameValuePair "vicinae/themes/${name}.${themeExtension}" {
+            source = themeFormat.generate "vicinae-${name}-theme" theme;
+          }
+        ) cfg.themes;
+      in
+      {
+        configFile = {
+          "vicinae/vicinae.json" = lib.mkIf (cfg.settings != { }) {
+            source = jsonFormat.generate "vicinae-settings" cfg.settings;
+          };
         }
-      ) cfg.themes;
+        // lib.optionalAttrs (!themeIsToml) themeFiles;
 
-      dataFile = builtins.listToAttrs (
-        builtins.map (item: {
-          name = "vicinae/extensions/${item.name}";
-          value.source = item;
-        }) cfg.extensions
-      );
-    };
+        dataFile =
+          builtins.listToAttrs (
+            builtins.map (item: {
+              name = "vicinae/extensions/${item.name}";
+              value.source = item;
+            }) cfg.extensions
+          )
+          // lib.optionalAttrs themeIsToml themeFiles;
+      };
 
     systemd.user.services.vicinae = lib.mkIf (cfg.systemd.enable && cfg.package != null) {
       Unit = {
diff --git a/tests/modules/programs/vicinae/example-settings.nix b/tests/modules/programs/vicinae/example-settings.nix
index b9de5f24f..3e914781e 100644
--- a/tests/modules/programs/vicinae/example-settings.nix
+++ b/tests/modules/programs/vicinae/example-settings.nix
@@ -28,22 +28,34 @@
       };
     };
     themes = {
-      base16-default-dark = {
-        version = "1.0.0";
-        appearance = "dark";
-        name = "base16 default dark";
-        description = "base16 default dark by Chris Kempson";
-        palette = {
-          background = "#181818";
-          foreground = "#d8d8d8";
-          blue = "#7cafc2";
-          green = "#a3be8c";
-          magenta = "#ba8baf";
-          orange = "#dc9656";
-          purple = "#a16946";
-          red = "#ab4642";
-          yellow = "#f7ca88";
-          cyan = "#86c1b9";
+      catppuccin-mocha = {
+        meta = {
+          version = 1;
+          name = "Catppuccin Mocha";
+          description = "Cozy feeling with color-rich accents";
+          variant = "dark";
+          icon = "icons/catppuccin-mocha.png";
+          inherits = "vicinae-dark";
+        };
+
+        colors = {
+          core = {
+            background = "#1E1E2E";
+            foreground = "#CDD6F4";
+            secondary_background = "#181825";
+            border = "#313244";
+            accent = "#89B4FA";
+          };
+          accents = {
+            blue = "#89B4FA";
+            green = "#A6E3A1";
+            magenta = "#F5C2E7";
+            orange = "#FAB387";
+            purple = "#CBA6F7";
+            red = "#F38BA8";
+            yellow = "#F9E2AF";
+            cyan = "#94E2D5";
+          };
         };
       };
     };
@@ -71,6 +83,7 @@
   nmt.script = ''
     assertFileExists      "home-files/.config/vicinae/vicinae.json"
     assertFileExists      "home-files/.config/systemd/user/vicinae.service"
+    assertFileExists      "home-files/.local/share/vicinae/themes/catppuccin-mocha.toml"
     assertFileExists      "home-files/.local/share/vicinae/extensions/gif-search/package.json"
     assertFileExists      "home-files/.local/share/vicinae/extensions/test-extension/package.json"
   '';