diff --git a/CHANGELOG-WIP.md b/CHANGELOG-WIP.md
index ce7f98eddb3..313fb09976a 100644
--- a/CHANGELOG-WIP.md
+++ b/CHANGELOG-WIP.md
@@ -54,6 +54,7 @@
 - The `duration` Twig filter now has a `language` argument. ([#16332](https://github.com/craftcms/cms/pull/16332))
 - The `indexOf` Twig filter now has a `default` argument, which can be any integer or `null`. (`-1` by default for backwards compatibility.)
 - It’s now possible to reference custom field handles in element queries’ `where` params. ([#16318](https://github.com/craftcms/cms/pull/16318))
+- Deprecated the `ucfirst` Twig filter. `capitalize` should be used instead.
 
 ### Extensibility
 - Added `craft\base\Element::EVENT_DEFINE_ALT_ACTIONS`. ([#16294](https://github.com/craftcms/cms/pull/16294))
diff --git a/src/templates/settings/plugins/index.twig b/src/templates/settings/plugins/index.twig
index f1cc1219e4c..7d75657fc64 100644
--- a/src/templates/settings/plugins/index.twig
+++ b/src/templates/settings/plugins/index.twig
@@ -188,7 +188,7 @@
                       {% switch issue %}
                       {% case 'wrong_edition' %}
                         {{ 'This license is for the {name} edition.'|t('app', {
-                          name: config.licensedEdition|ucfirst
+                          name: config.licensedEdition|capitalize,
                         }) }}
                       {% case 'no_trials' %}
                         {{ 'Plugin trials are not allowed on this domain.'|t('app') }}
diff --git a/src/web/twig/Extension.php b/src/web/twig/Extension.php
index 95194aa0fd6..97d3373fee8 100644
--- a/src/web/twig/Extension.php
+++ b/src/web/twig/Extension.php
@@ -462,9 +462,11 @@ public function truncateFilter(string $string, int $length, string $suffix = '
      *
      * @param mixed $string The multibyte string.
      * @return string The string with the first character converted to upercase.
+     * @deprecated in 5.6.0
      */
     public function ucfirstFilter(mixed $string): string
     {
+        Craft::$app->getDeprecator()->log('ucfirst', 'The `|ucfirst` filter has been deprecated. Use `|capitalize` instead.');
         return StringHelper::upperCaseFirst((string)$string);
     }
 
@@ -474,6 +476,7 @@ public function ucfirstFilter(mixed $string): string
      * @param TwigEnvironment $env
      * @param string $string
      * @return string
+     * @deprecated in 3.5.0
      */
     public function ucwordsFilter(TwigEnvironment $env, string $string): string
     {