As a redshirt freshman in 2019, he was named the starter at left defensive end, recording 44 tackles (3 for loss), one sack, and 4 pass deflections (tied for second on the team).[4]
As a sophomore in 2020, the season was reduced to 8 games because of the COVID-19 pandemic. He started all 8 games, collecting 36 tackles (fifth on the team), 12.5 tackles for loss (led the conference), 6 sacks (second on the team), one pass deflection, and one fumble recovered. He had 6 tackles (2 for loss) and one sack against the University of New Mexico. He was named first-team All-Mountain West for the first time in his career.[5][6]
As a junior in 2021, he started all 12 games, registering 37 tackles, 10.5 tackles for loss (led the team), 6 sacks (led the team), 3 forced fumbles (led the team), and deflected six passes. He had 7 tackles against the University of Wyoming. He was named first-team All-Mountain West for the second time.[7][8]
As a senior in 2022, he started in all 12 games, posting a career-high 69 tackles (third on the team), 19 tackles for loss (fifth in the nation), 9 sacks (led the team), two forced fumbles, one fumble recovery, and one deflected pass.[9][10] He had 7 tackles (3 for loss), one sack, one forced fumble and one fumble recovery against Fresno State University. He made 12 tackles (4.5 for loss), 2 sacks and one forced fumble against the University of Nevada. He had 5 tackles (3 for loss) and two sacks against Colorado State University. He was named the Mountain West Defensive Player of the Year and first-team All-Mountain West for the third straight year.[11][12][13]
He finished his career with 191 tackles, 46 tackles for loss (second in school history), 23 sacks (fifth in school history), 14 pass deflections, 5 forced fumbles and 2 fumble recoveries in 48 games played.
Fehoko was selected by the Dallas Cowboys in the fourth round (129th overall) of the 2023 NFL draft.[16] The Cowboys placed him on injured reserve with a knee injury on November 18, 2023.[17] He was activated on January 3, 2024.