Can supplications (duas) be made in Turkish during the Friday sermon (khutbah)?

It is not a requirement for supplications to be made in a specific language. Supplication (dua) is the servant turning to Almighty Allah, pleading with Him, and asking from Him. Therefore, there is no objection to a person making supplication in their own language in a way that they understand what they are asking for. However, it is preferable to recite supplications found in the Qur’an or transmitted from the Prophet (peace be upon him) in their original forms as much as possible. In this regard, efforts should be made to recite the supplications of the khutbah in their original forms. Nevertheless, there is no obstacle to making a supplication at the end of the second sermon in a language that the congregation can understand.

Source: T.C. Diyanet İşleri Başkanlığı, Din İşleri Yüksek Kurulu