Early career Arnett started his professional MMA career in 2012 and fought primarily on the regional circuit of the
Pacific Northwest United States. He amassed a record of 15–3 before signed by UFC.
Dana White's Tuesday Night Contention Series Arnett faced
Brandon Davis on August 1, 2017, at
Dana White's Contender Series 4.
Ultimate Fighting Championship Arnett made his promotional debut on January 27, 2018, against
Cory Sandhagen at
UFC on Fox 27. He lost the fight via technical knockout in round two. Arnett faced
Hakeem Dawodu on July 28, 2018, at
UFC on Fox 30. He lost the fight via unanimous decision. Arnett faced
Humberto Bandenay on November 17, 2018, at
UFC Fight Night: Magny vs. Ponzinibbio. He won the fight via unanimous decision. Arnett faced
Shane Young on February 10, 2019, at
UFC 234. He lost the fight via unanimous decision. On July 7, 2019, it was reported that Arnett was released by the UFC.
Post-UFC career After the release, Arnett was scheduled to challenge
Rolando Dy for the UAE Warriors Featherweight Championship at UAE Warriors 8 on October 19, 2019. However, Arnett withdrew from the bout and was replaced by Do Gyeom Lee. He made his promotional debut against Elias Boudegzdame at UAE Warriors 10 on January 31, 2020. He lost the fight via unanimous decision. Arnett was scheduled to face Dinis Paiva in a featherweight bout at CES MMA 61 on April 24, 2020. However, the event was postponed indefinitely due to the
COVID-19 pandemic. Arnett faced Daniel Vega in a catchweight bout at UAE Warriors 18 on March 20, 2021. He won the fight via third-round knockout. Arnett is now again scheduled to challenge for the UAE Warriors Featherweight Championship against Do Gyeom Lee at UAE Warriors 24 on October 29, 2021. ==Mixed martial arts record==