Early career

After an amateur career in 2012 and 2013 where he held a record of 4–7, Nicholson made his professional MMA debut in February 2014. He amassed a record of 6 wins against 1 loss before signing with the Ultimate Fighting Championship.

Ultimate Fighting Championship

Nicholson made his UFC debut on February 6, 2016, at UFC Fight Night: Hendricks vs. Thompson. He faced Misha Cirkunov on the card^[5] and lost the fight via submission in the second round.^[6]

In his second fight for the promotion, Nicholson faced Devin Clark in a Middleweight bout at UFC Fight Night: McDonald vs. Lineker on July 13, 2016.^[7] He won the fight via knockout in the first round.^[8]

In his third fight for the promotion, Nicholson faced Sam Alvey at UFC Fight Night: dos Anjos vs. Ferguson on November 5, 2016.^[9] He lost the fight by unanimous decision.^[10]

In his fourth fight for the promotion, Nicholson faced Jack Hermansson at UFC Fight Night: Gustafsson vs. Teixeira on May 28, 2017.^[11] He lost the fight via TKO in the first round. Subsequent to this fight, Nicholson was released from the promotion.^[12]

Professional Fighters League

In June 2018, Nicholson entered into the $1 million Heavyweight tournament held by Professional Fighters League. He faced |Jake Heun in the opening round at PFL 1 on June 7, 2018. He won the fight via knockout due to a flying knee in the second round.^[13] On July 19, Nicholson lost via TKO to Phillipe Lins at PFL 4.^[14] In October 2018, Nicholson defeated Jack May by TKO^[15] but then lost later that night via KO to Josh Copeland.^[16]

In June 2019, Nicholson entered the second season of PFL's Heavyweight tournament and lost a decision to Francimar Barroso. In August, he defeated Zeke Tuinei-Wiley. On October 31, Nicholson lost a rematch against Barroso again by decision. In December 2019, Nicholson was suspended by the Nevada State Athletic Commission for four years due to testing positive for three steroids.^[17]

Regional circuit

Nicholson was scheduled to headline Gamebred FC 2 against Antônio Silva on September 11, 2021.^[18] However, Silva's prevailing contract with Eagle Fighting Championship prevented him from competing at the event and he was initially replaced by Jack May. In turn, May tested positive for COVID-19 and was replaced by Jonathan Ivey. Furthermore, the event was postponed to take place on October 1, 2021, in order to ensure housing for those impacted of Hurricane Ida.^[19] He won the bout via TKO in the first round.^[20]

Nicholson faced Tony Lopez on December 17, 2021, at Gamebred FC 3. He won the bout via KO in the first round.^[20]

Nicholson faced Oscar Sosa for the Titan FC Heavyweight Championship on July 29, 2022, at Titan FC 78. He won the bout and title via anaconda choke in the first round.^[21]

Nicholson defended his title against Valter Ignacio at Titan FC 82/ SBC 47: Revenge on June 2, 2023. losing the bout in the fourth round after tapping out due to injury.^[22]

Nicholson faced Prince McLean at Gamebred Bareknuckle MMA 6 on November 10, 2023.^[23] He won the fight via knockout 19 seconds into the bout.^[24]

Nicholson faced Chase Sherman at Gamebred Bareknuckle MMA 7 on March 2, 2024.^[25] Nicholson lost in the first round by way of knockout.^[26]