Dubrov was selected by Roscosmos as a cosmonaut on 8 October 2012, as one of eight cosmonauts selected as part of Roscosmos's 2012 selection group. In 2020 he was assigned to the backup crew of Soyuz MS-17, backing up Russian cosmonaut Sergey Kud-Sverchkov as Flight Engineer on ISS Expedition 63/64