Cirkunov made his professional debut in January 2010 and amassed a record of 9-2 before signing with the Ultimate Fighting Championship in the summer of 2015.
Cirkunov was expected to make his promotional debut against Sean O'Connell on August 23, 2015 at UFC Fight Night 74. O'Connell withdrew from the bout due to injury and was replaced by Daniel Jolly. Cirkunov defeated Jolly via first round KO after achieving full mount and battering him when he turned his back.
Cirkunov faced Nikita Krylov on December 10, 2016 at UFC 206. He won the fight via submission in the first round.
Cirkunov was scheduled to face Glover Teixeira on October 28, 2017 at UFC Fight Night 119. However, the pairing was delayed after a recent hand surgery for Teixeira was slow to heal and the bout eventually took place on December 16, 2017 at UFC on Fox 26. Cirkunov lost the fight via TKO in the first round.