Oezdemir was signed by the UFC in 2017, and made his promotional debut as a short notice injury replacement against Ovince St. Preux on 4 February 2017 at UFC Fight Night 104. Oezdemir defeated St. Preux by split decision in the third fight of the main card. In his second fight for the promotion, Oezdemir faced Misha Cirkunov on 28 May 2017, at UFC Fight Night 109. He won the fight via knockout just 28 seconds into the first round. Oezdemir next faced third ranked Jimi Manuwa on 29 July 2017, at UFC 214. He won the fight via knockout in the fight's opening minute and subsequently won a Performance of the Night bonus. Oezdemir faced Daniel Cormier on 20 January 2018 at UFC 220 for the Light Heavyweight Championship. He lost the fight in the 2nd round by TKO. Oezdemir was expected to face Maurício Rua on 12 May 2018 at UFC Fight Night 129. However it was reported on 13 April 2018 that Oezdemir was pulled from the event due to alleged visa issues restricting his travel to Chile. The pairing was left intact and rescheduled for 22 July 2018 at UFC Fight Night 134. On 2 July 2018, it was reported that the Oezdemir would face Alexander Gustafsson instead on 4 August 2018 at UFC 227. However, on 19 July 2018 it was reported that Oezdemir was removed from the bout due to a broken nose. Oezdemir faced Anthony Smith on 27 October 2018 at UFC Fight Night 138. He lost the fight via a rear-naked choke submission in the third round. Oezdemir faced Dominick Reyes on 16 March 2019 at UFC on ESPN+ 5. He lost the fight via controversial split decision. Oezdemir was expected to face Ilir Latifi on 1 June 2019 at UFC Fight Night 153. On May 30, 2019 it was reported that Latifi was forced to pull out of the event due to back injury and the bout was cancelled. The pair was rebooked at UFC on ESPN 5 on August 3, 2019. In turn, due to Oezemir visa issues to enter United States, the bout was moved to UFC on ESPN+ 14. He won the fight via knockout in the second round. This win earned him the Performance of the Night award. Oezdemir faced Aleksandar Rakić on December 21, 2019 at UFC on ESPN+ 23. He won the fight via a split decision. In April 2020, Oezdemir revealed that he had renewed his contract with the UFC. Oezdemi faced promotional newcomer Jiří Procházka on July 11 at UFC 251. He lost the fight by knockout in the second round.
Kickboxing career
Oezdemir also holds a record of 5–0 in professional kickboxing. He made his debut in SUPERKOMBAT, the largest kickboxing organization in Europe, in 2014.
Personal life
Aggravated battery incident
On 19 November 2017 Volkan was arrested for aggravated battery. His bail was reportedly set at $10,000. On 9 July 2018, Oezdemir informed that the charges pressed against him were dropped.
