He was elected to the Turkish parliament for Kars as a representative for the HDP in the general election of June 2015, and again the snap elections of November 2015. He supported the defense of Kobani against the Islamic State of Iraq and Levant (ISIL) in Kobani and was prosecuted for taking part in manifestations in October 2014 during the Siege of Kobani. He was arrested in spring 2017 and released in September of the same year. During his parliamentary career he advocated for Human Rights, Kurdish rights and the protection of the environment. In the local elections of March 2019 he was elected the Mayor of Kars. In May 2020, after several Municipalities won by the HDP were put under the authority of state appointed trustees, Bilgen received the support from dozens of human rights organization. On 2 October 2020, he was formally arrested and deposed as Mayor of Kars and replaced by a government-appointed trustee, the governor of Kars Province, Eyüp Tepe.