Due to NCAA rules, Shelvin was an academic redshirt during his true freshman season.[1] Sitting at third-string on the depth chart at nose tackle during his redshirt freshman season, Shelvin was suspended for two weeks by the team for discipline issues.[1] He cracked the starting lineup during his sophomore season.[1] He won a national championship with LSU during his 2019 sophomore season.[7] On January 15, 2020, Shelvin announced his intention to stay in college for his junior season.[8]
Shelvin was drafted by the Cincinnati Bengals in the fourth round, 122nd overall, of the 2021 NFL draft.[12] He signed his four-year rookie contract with Cincinnati on May 17.[13]
Playing sparingly, Shelvin played in 3 regular season games as a rookie, recording 4 tackles in a week 18 loss to the Cleveland Browns. After being declared inactive during the Bengals' Wild Card win against the Las Vegas Raiders, Shelvin would play in the Bengals' playoff wins against the Tennessee Titans and Kansas City Chiefs respectively, however Shelvin recorded no stats in either playoff game. Shelvin did not play in the Bengals' 23–20 loss in Super Bowl LVI.[14]
On August 30, 2022, Shelvin was waived by the Bengals and signed to the practice squad the next day.[15][16] He was released on December 6.[17]
Tennessee Titans
On January 23, 2023, Shelvin signed a reserve/future contract with the Titans.[18] He was waived on August 29.[19]