diff --git a/docs/management/advanced-options.asciidoc b/docs/management/advanced-options.asciidoc
index fde70b5ffca0e..a2af3b91931af 100644
--- a/docs/management/advanced-options.asciidoc
+++ b/docs/management/advanced-options.asciidoc
@@ -187,7 +187,7 @@ this setting stores part of the URL in your browser session to keep the URL
 short.
 
 [[theme-darkmode]]`theme:darkMode`::
-The UI theme that the {kib} UI should use.
+deprecated:[9.0.0] The UI theme that the {kib} UI should use.
 Set to `enabled` or `disabled` to enable or disable the dark theme.
 Set to `system` to have the {kib} UI theme follow the system theme.
 You must refresh the page to apply the setting.
diff --git a/packages/core/ui-settings/core-ui-settings-server-internal/src/settings/theme.ts b/packages/core/ui-settings/core-ui-settings-server-internal/src/settings/theme.ts
index 36324f951952e..7ee214fa5d071 100644
--- a/packages/core/ui-settings/core-ui-settings-server-internal/src/settings/theme.ts
+++ b/packages/core/ui-settings/core-ui-settings-server-internal/src/settings/theme.ts
@@ -65,6 +65,12 @@ export const getThemeSettings = (
           defaultMessage: `Sync with system`,
         }),
       },
+      deprecation: {
+        message: i18n.translate('core.ui_settings.params.darkModeDeprecation', {
+          defaultMessage: 'This setting is deprecated and will be removed in Kibana 10.0.',
+        }),
+        docLinksKey: 'generalSettings',
+      },
       requiresPageReload: true,
       schema: schema.oneOf([
         schema.literal('enabled'),