diff --git a/docs/source/configuration/validation.md b/docs/source/configuration/validation.md
index c76e95e42d..89386cda8f 100644
--- a/docs/source/configuration/validation.md
+++ b/docs/source/configuration/validation.md
@@ -95,6 +95,7 @@ In the following example, the `urlValidator` method validator will be applied fo
 config.registerUtility({
   type: 'validator',
   name: 'url',
+  dependencies: { format: 'url' },
   method: urlValidator,
 })
 ```
diff --git a/packages/volto/locales/ca/LC_MESSAGES/volto.po b/packages/volto/locales/ca/LC_MESSAGES/volto.po
index 3e7b0dfe67..3a7b648f4f 100644
--- a/packages/volto/locales/ca/LC_MESSAGES/volto.po
+++ b/packages/volto/locales/ca/LC_MESSAGES/volto.po
@@ -3769,6 +3769,11 @@ msgstr ""
 msgid "The registration process has been successful. Please check your e-mail inbox for information on how activate your account."
 msgstr "El procés de registre ha estat satisfactori. Si us plau, comproveu la vostra bústia d'entrada de correu electrònic per obtenir informació sobre com activar el vostre compte."
 
+#. Default: "The selected default language must be in the list of the field 'Available languages'"
+#: helpers/MessageLabels/MessageLabels
+msgid "The selected default language must be in the list of the field 'Available languages'"
+msgstr ""
+
 #. Default: "The site configuration is outdated and needs to be upgraded."
 #: components/manage/Controlpanels/Controlpanels
 #: components/manage/Controlpanels/UpgradeControlPanel
diff --git a/packages/volto/locales/de/LC_MESSAGES/volto.po b/packages/volto/locales/de/LC_MESSAGES/volto.po
index 043109a013..488a8cfe1f 100644
--- a/packages/volto/locales/de/LC_MESSAGES/volto.po
+++ b/packages/volto/locales/de/LC_MESSAGES/volto.po
@@ -3768,6 +3768,11 @@ msgstr "Die angegebene alternative URL existiert bereits."
 msgid "The registration process has been successful. Please check your e-mail inbox for information on how activate your account."
 msgstr "Bitte prüfen Sie Ihr E-Mail Postfach. Sie sollten eine E-Mail erhalten haben mit Anweisungen, wie Sie Ihren Zugang aktivieren können."
 
+#. Default: "The selected default language must be in the list of the field 'Available languages'"
+#: helpers/MessageLabels/MessageLabels
+msgid "The selected default language must be in the list of the field 'Available languages'"
+msgstr ""
+
 #. Default: "The site configuration is outdated and needs to be upgraded."
 #: components/manage/Controlpanels/Controlpanels
 #: components/manage/Controlpanels/UpgradeControlPanel
diff --git a/packages/volto/locales/en/LC_MESSAGES/volto.po b/packages/volto/locales/en/LC_MESSAGES/volto.po
index 9ad7a604aa..2bc13ebd8a 100644
--- a/packages/volto/locales/en/LC_MESSAGES/volto.po
+++ b/packages/volto/locales/en/LC_MESSAGES/volto.po
@@ -3763,6 +3763,11 @@ msgstr ""
 msgid "The registration process has been successful. Please check your e-mail inbox for information on how activate your account."
 msgstr ""
 
+#. Default: "The selected default language must be in the list of the field 'Available languages'"
+#: helpers/MessageLabels/MessageLabels
+msgid "The selected default language must be in the list of the field 'Available languages'"
+msgstr ""
+
 #. Default: "The site configuration is outdated and needs to be upgraded."
 #: components/manage/Controlpanels/Controlpanels
 #: components/manage/Controlpanels/UpgradeControlPanel
diff --git a/packages/volto/locales/es/LC_MESSAGES/volto.po b/packages/volto/locales/es/LC_MESSAGES/volto.po
index ff5b8c2299..83a0b90e5d 100644
--- a/packages/volto/locales/es/LC_MESSAGES/volto.po
+++ b/packages/volto/locales/es/LC_MESSAGES/volto.po
@@ -3770,6 +3770,11 @@ msgstr "¡La URL alternativa ya existe!"
 msgid "The registration process has been successful. Please check your e-mail inbox for information on how activate your account."
 msgstr "El registro fue exitoso. Por favor, verifique su bandeja de entrada para obtener información sobre cómo activar su cuenta."
 
+#. Default: "The selected default language must be in the list of the field 'Available languages'"
+#: helpers/MessageLabels/MessageLabels
+msgid "The selected default language must be in the list of the field 'Available languages'"
+msgstr ""
+
 #. Default: "The site configuration is outdated and needs to be upgraded."
 #: components/manage/Controlpanels/Controlpanels
 #: components/manage/Controlpanels/UpgradeControlPanel
diff --git a/packages/volto/locales/eu/LC_MESSAGES/volto.po b/packages/volto/locales/eu/LC_MESSAGES/volto.po
index aa260e34fa..f81da30b43 100644
--- a/packages/volto/locales/eu/LC_MESSAGES/volto.po
+++ b/packages/volto/locales/eu/LC_MESSAGES/volto.po
@@ -3770,6 +3770,11 @@ msgstr "Eman duzun ordezko bidea jada badago!"
 msgid "The registration process has been successful. Please check your e-mail inbox for information on how activate your account."
 msgstr "Izen-emate prozesua ondo egin duzu. Begiratu zure eposta, kontua aktibatzeko informazioa bertara bidali dizugu-eta."
 
+#. Default: "The selected default language must be in the list of the field 'Available languages'"
+#: helpers/MessageLabels/MessageLabels
+msgid "The selected default language must be in the list of the field 'Available languages'"
+msgstr ""
+
 #. Default: "The site configuration is outdated and needs to be upgraded."
 #: components/manage/Controlpanels/Controlpanels
 #: components/manage/Controlpanels/UpgradeControlPanel
diff --git a/packages/volto/locales/fi/LC_MESSAGES/volto.po b/packages/volto/locales/fi/LC_MESSAGES/volto.po
index 99c1f6ff04..fcb0c55a08 100644
--- a/packages/volto/locales/fi/LC_MESSAGES/volto.po
+++ b/packages/volto/locales/fi/LC_MESSAGES/volto.po
@@ -3768,6 +3768,11 @@ msgstr "Ehdotettu vaihtoehtoinen URL on jo olemassa!"
 msgid "The registration process has been successful. Please check your e-mail inbox for information on how activate your account."
 msgstr "Rekisteröinti onnistui. Tarkista, saitko sähköpostiisi ohjeet käyttäjätunnuksesi aktivoimiseksi."
 
+#. Default: "The selected default language must be in the list of the field 'Available languages'"
+#: helpers/MessageLabels/MessageLabels
+msgid "The selected default language must be in the list of the field 'Available languages'"
+msgstr ""
+
 #. Default: "The site configuration is outdated and needs to be upgraded."
 #: components/manage/Controlpanels/Controlpanels
 #: components/manage/Controlpanels/UpgradeControlPanel
diff --git a/packages/volto/locales/fr/LC_MESSAGES/volto.po b/packages/volto/locales/fr/LC_MESSAGES/volto.po
index 120eda4ebe..1ccd02ec8e 100644
--- a/packages/volto/locales/fr/LC_MESSAGES/volto.po
+++ b/packages/volto/locales/fr/LC_MESSAGES/volto.po
@@ -3770,6 +3770,11 @@ msgstr "L'URL alternative fournie existe déjà !"
 msgid "The registration process has been successful. Please check your e-mail inbox for information on how activate your account."
 msgstr "Le processus d'inscription a réussi. Veuillez vérifier votre boîte e-mail pour savoir comment activer votre compte."
 
+#. Default: "The selected default language must be in the list of the field 'Available languages'"
+#: helpers/MessageLabels/MessageLabels
+msgid "The selected default language must be in the list of the field 'Available languages'"
+msgstr ""
+
 #. Default: "The site configuration is outdated and needs to be upgraded."
 #: components/manage/Controlpanels/Controlpanels
 #: components/manage/Controlpanels/UpgradeControlPanel
diff --git a/packages/volto/locales/hi/LC_MESSAGES/volto.po b/packages/volto/locales/hi/LC_MESSAGES/volto.po
index 0219651642..a3035d37c5 100644
--- a/packages/volto/locales/hi/LC_MESSAGES/volto.po
+++ b/packages/volto/locales/hi/LC_MESSAGES/volto.po
@@ -3763,6 +3763,11 @@ msgstr "प्रदान किया गया वैकल्पिक य
 msgid "The registration process has been successful. Please check your e-mail inbox for information on how activate your account."
 msgstr "रजिस्ट्रेशन प्रक्रिया सफल रही है। कृपया अपने ईमेल इनबॉक्स में अपने खाते को सक्रिय करने के लिए जानकारी के लिए जाँच करें।"
 
+#. Default: "The selected default language must be in the list of the field 'Available languages'"
+#: helpers/MessageLabels/MessageLabels
+msgid "The selected default language must be in the list of the field 'Available languages'"
+msgstr ""
+
 #. Default: "The site configuration is outdated and needs to be upgraded."
 #: components/manage/Controlpanels/Controlpanels
 #: components/manage/Controlpanels/UpgradeControlPanel
diff --git a/packages/volto/locales/it/LC_MESSAGES/volto.po b/packages/volto/locales/it/LC_MESSAGES/volto.po
index 6cccb3d46b..b3f927a447 100644
--- a/packages/volto/locales/it/LC_MESSAGES/volto.po
+++ b/packages/volto/locales/it/LC_MESSAGES/volto.po
@@ -3763,6 +3763,11 @@ msgstr "L'url alternativo inserito è già stato utilizzato!"
 msgid "The registration process has been successful. Please check your e-mail inbox for information on how activate your account."
 msgstr "La registrazione è avvenuta correttamente. Per favore controlla la tua casella di posta per informazioni su come attivare il tuo account."
 
+#. Default: "The selected default language must be in the list of the field 'Available languages'"
+#: helpers/MessageLabels/MessageLabels
+msgid "The selected default language must be in the list of the field 'Available languages'"
+msgstr ""
+
 #. Default: "The site configuration is outdated and needs to be upgraded."
 #: components/manage/Controlpanels/Controlpanels
 #: components/manage/Controlpanels/UpgradeControlPanel
diff --git a/packages/volto/locales/ja/LC_MESSAGES/volto.po b/packages/volto/locales/ja/LC_MESSAGES/volto.po
index e4c74c3188..67b0f0bd4a 100644
--- a/packages/volto/locales/ja/LC_MESSAGES/volto.po
+++ b/packages/volto/locales/ja/LC_MESSAGES/volto.po
@@ -3768,6 +3768,11 @@ msgstr ""
 msgid "The registration process has been successful. Please check your e-mail inbox for information on how activate your account."
 msgstr "The registration process has been successful. Please check your e-mail inbox for information on how activate your account. (未翻訳)"
 
+#. Default: "The selected default language must be in the list of the field 'Available languages'"
+#: helpers/MessageLabels/MessageLabels
+msgid "The selected default language must be in the list of the field 'Available languages'"
+msgstr ""
+
 #. Default: "The site configuration is outdated and needs to be upgraded."
 #: components/manage/Controlpanels/Controlpanels
 #: components/manage/Controlpanels/UpgradeControlPanel
diff --git a/packages/volto/locales/nl/LC_MESSAGES/volto.po b/packages/volto/locales/nl/LC_MESSAGES/volto.po
index 1b80a4e983..db507c0b13 100644
--- a/packages/volto/locales/nl/LC_MESSAGES/volto.po
+++ b/packages/volto/locales/nl/LC_MESSAGES/volto.po
@@ -3767,6 +3767,11 @@ msgstr "De ingevoerde alternatieve URL bestaat reeds!"
 msgid "The registration process has been successful. Please check your e-mail inbox for information on how activate your account."
 msgstr "Het registratieproces was succesvol. Controleer jouw e-mails voor informatie over hoe jouw account te activeren."
 
+#. Default: "The selected default language must be in the list of the field 'Available languages'"
+#: helpers/MessageLabels/MessageLabels
+msgid "The selected default language must be in the list of the field 'Available languages'"
+msgstr ""
+
 #. Default: "The site configuration is outdated and needs to be upgraded."
 #: components/manage/Controlpanels/Controlpanels
 #: components/manage/Controlpanels/UpgradeControlPanel
diff --git a/packages/volto/locales/pt/LC_MESSAGES/volto.po b/packages/volto/locales/pt/LC_MESSAGES/volto.po
index 8f4040495a..c492f3205d 100644
--- a/packages/volto/locales/pt/LC_MESSAGES/volto.po
+++ b/packages/volto/locales/pt/LC_MESSAGES/volto.po
@@ -3768,6 +3768,11 @@ msgstr ""
 msgid "The registration process has been successful. Please check your e-mail inbox for information on how activate your account."
 msgstr "O processo de registo foi bem sucedido. Por favor verifique no seu e-mail a informação sobre como activar a sua conta."
 
+#. Default: "The selected default language must be in the list of the field 'Available languages'"
+#: helpers/MessageLabels/MessageLabels
+msgid "The selected default language must be in the list of the field 'Available languages'"
+msgstr ""
+
 #. Default: "The site configuration is outdated and needs to be upgraded."
 #: components/manage/Controlpanels/Controlpanels
 #: components/manage/Controlpanels/UpgradeControlPanel
diff --git a/packages/volto/locales/pt_BR/LC_MESSAGES/volto.po b/packages/volto/locales/pt_BR/LC_MESSAGES/volto.po
index 76a25c310c..ff04341f97 100644
--- a/packages/volto/locales/pt_BR/LC_MESSAGES/volto.po
+++ b/packages/volto/locales/pt_BR/LC_MESSAGES/volto.po
@@ -3769,6 +3769,11 @@ msgstr "A URL alternativa já existe!"
 msgid "The registration process has been successful. Please check your e-mail inbox for information on how activate your account."
 msgstr "O processo de registro foi bem sucedido. Verifique sua caixa de entrada de e-mail para obter informações sobre como ativar sua conta."
 
+#. Default: "The selected default language must be in the list of the field 'Available languages'"
+#: helpers/MessageLabels/MessageLabels
+msgid "The selected default language must be in the list of the field 'Available languages'"
+msgstr ""
+
 #. Default: "The site configuration is outdated and needs to be upgraded."
 #: components/manage/Controlpanels/Controlpanels
 #: components/manage/Controlpanels/UpgradeControlPanel
diff --git a/packages/volto/locales/ro/LC_MESSAGES/volto.po b/packages/volto/locales/ro/LC_MESSAGES/volto.po
index 9199570724..b85e3efedb 100644
--- a/packages/volto/locales/ro/LC_MESSAGES/volto.po
+++ b/packages/volto/locales/ro/LC_MESSAGES/volto.po
@@ -3769,6 +3769,11 @@ msgstr "URL-ul alternativ furnizat există deja!"
 msgid "The registration process has been successful. Please check your e-mail inbox for information on how activate your account."
 msgstr "Procesul de înregistrare a avut succes. Vă rugăm să verificați căsuța de e-mail pentru informații despre modul de activare a contului dvs."
 
+#. Default: "The selected default language must be in the list of the field 'Available languages'"
+#: helpers/MessageLabels/MessageLabels
+msgid "The selected default language must be in the list of the field 'Available languages'"
+msgstr ""
+
 #. Default: "The site configuration is outdated and needs to be upgraded."
 #: components/manage/Controlpanels/Controlpanels
 #: components/manage/Controlpanels/UpgradeControlPanel
diff --git a/packages/volto/locales/volto.pot b/packages/volto/locales/volto.pot
index 18436bc9bf..4e28b791e4 100644
--- a/packages/volto/locales/volto.pot
+++ b/packages/volto/locales/volto.pot
@@ -1,7 +1,7 @@
 msgid ""
 msgstr ""
 "Project-Id-Version: Plone\n"
-"POT-Creation-Date: 2024-12-06T13:45:21.266Z\n"
+"POT-Creation-Date: 2025-03-05T13:04:20.470Z\n"
 "Last-Translator: Plone i18n <plone-i18n@lists.sourceforge.net>\n"
 "Language-Team: Plone i18n <plone-i18n@lists.sourceforge.net>\n"
 "Content-Type: text/plain; charset=utf-8\n"
@@ -3765,6 +3765,11 @@ msgstr ""
 msgid "The registration process has been successful. Please check your e-mail inbox for information on how activate your account."
 msgstr ""
 
+#. Default: "The selected default language must be in the list of the field 'Available languages'"
+#: helpers/MessageLabels/MessageLabels
+msgid "The selected default language must be in the list of the field 'Available languages'"
+msgstr ""
+
 #. Default: "The site configuration is outdated and needs to be upgraded."
 #: components/manage/Controlpanels/Controlpanels
 #: components/manage/Controlpanels/UpgradeControlPanel
diff --git a/packages/volto/locales/zh_CN/LC_MESSAGES/volto.po b/packages/volto/locales/zh_CN/LC_MESSAGES/volto.po
index 8b3aa94303..2aabbf9f16 100644
--- a/packages/volto/locales/zh_CN/LC_MESSAGES/volto.po
+++ b/packages/volto/locales/zh_CN/LC_MESSAGES/volto.po
@@ -3769,6 +3769,11 @@ msgstr "提供的替代url已经存在!"
 msgid "The registration process has been successful. Please check your e-mail inbox for information on how activate your account."
 msgstr "注册过程成功完成。请在您的电子邮箱中查看有关如何激活账户的信息。"
 
+#. Default: "The selected default language must be in the list of the field 'Available languages'"
+#: helpers/MessageLabels/MessageLabels
+msgid "The selected default language must be in the list of the field 'Available languages'"
+msgstr ""
+
 #. Default: "The site configuration is outdated and needs to be upgraded."
 #: components/manage/Controlpanels/Controlpanels
 #: components/manage/Controlpanels/UpgradeControlPanel
diff --git a/packages/volto/news/6811.feature b/packages/volto/news/6811.feature
new file mode 100644
index 0000000000..fb3195b385
--- /dev/null
+++ b/packages/volto/news/6811.feature
@@ -0,0 +1 @@
+Add validator for `default_language` in language control panel. @sneridagh
diff --git a/packages/volto/src/components/manage/Widgets/SelectWidget.jsx b/packages/volto/src/components/manage/Widgets/SelectWidget.jsx
index 2321903b69..f9771fd4a6 100644
--- a/packages/volto/src/components/manage/Widgets/SelectWidget.jsx
+++ b/packages/volto/src/components/manage/Widgets/SelectWidget.jsx
@@ -251,6 +251,7 @@ class SelectWidget extends Component {
             this.props.placeholder ??
             this.props.intl.formatMessage(messages.select)
           }
+          onBlur={() => this.props.onBlur(id, value)}
           onChange={(selectedOption) => {
             if (isMulti) {
               return onChange(
diff --git a/packages/volto/src/config/validation.ts b/packages/volto/src/config/validation.ts
index 5a92e004e9..c46b1fa4c4 100644
--- a/packages/volto/src/config/validation.ts
+++ b/packages/volto/src/config/validation.ts
@@ -15,6 +15,7 @@ import {
   startEventDateRangeValidator,
   endEventDateRangeValidator,
   patternValidator,
+  defaultLanguageControlPanelValidator,
 } from '@plone/volto/helpers/FormValidation/validators';
 
 const registerValidators = (config: ConfigType) => {
@@ -150,6 +151,13 @@ const registerValidators = (config: ConfigType) => {
     dependencies: { behaviorName: 'plone.eventbasic', fieldName: 'end' },
     method: endEventDateRangeValidator,
   });
+
+  config.registerUtility({
+    name: 'default_language',
+    type: 'validator',
+    dependencies: { format: 'default_language' },
+    method: defaultLanguageControlPanelValidator,
+  });
 };
 
 export { registerValidators };
diff --git a/packages/volto/src/helpers/FormValidation/validators.ts b/packages/volto/src/helpers/FormValidation/validators.ts
index 7abc954fb8..16d57eb321 100644
--- a/packages/volto/src/helpers/FormValidation/validators.ts
+++ b/packages/volto/src/helpers/FormValidation/validators.ts
@@ -203,3 +203,17 @@ export const minItemsValidator = ({
     ? formatMessage(messages.minItems, { minItems: field.minItems })
     : null;
 };
+
+export const defaultLanguageControlPanelValidator = ({
+  value,
+  formData,
+  formatMessage,
+}: Validator) => {
+  const isValid =
+    value &&
+    (formData.available_languages.find(
+      (lang: { token: string }) => lang.token === value,
+    ) ||
+      formData.available_languages.includes(value));
+  return !isValid ? formatMessage(messages.defaultLanguage) : null;
+};
diff --git a/packages/volto/src/helpers/MessageLabels/MessageLabels.js b/packages/volto/src/helpers/MessageLabels/MessageLabels.js
index 7549e09043..bd64225a8d 100644
--- a/packages/volto/src/helpers/MessageLabels/MessageLabels.js
+++ b/packages/volto/src/helpers/MessageLabels/MessageLabels.js
@@ -403,4 +403,9 @@ export const messages = defineMessages({
     defaultMessage:
       'The number of items must be greater than or equal to {minItems}',
   },
+  defaultLanguage: {
+    id: "The selected default language must be in the list of the field 'Available languages'",
+    defaultMessage:
+      "The selected default language must be in the list of the field 'Available languages'",
+  },
 });