From 2016 until August 2021, he served in the Ukrainian "Azov" regiment as a driver and commander of a vehicle platoon. He was dismissed from service. In spring 2022, Mizhgorodsky was detained in Mariupol. He was accused of organizing the activities of a terrorist organization and the violent seizure or retention of power. Human rights activists note that he is a prisoner of war, therefore, he should not have been held criminally liable essentially for participating in combat operations, and beyond that, they consider the charges absurd. On March 26, 2025, Mizhgorodsky was sentenced to 17 years in a strict-regime penal colony.