Barmore redshirted his true freshman season.[2][3][4] As a redshirt freshman, he played in 12 games and made 26 tackles, including six tackles for loss and two sacks and was named to the SEC All-Freshman team.[5][6] Barmore was named first-team All-SEC as a redshirt sophomore, finishing the season with 37 total tackles, 9.5 tackles for loss, and eight sacks with three forced fumbles and three passes defended.[7][8] He was named the Defensive MVP of the 2021 College Football Playoff National Championship game after making five tackles, including two for a loss and one sack in Alabama's 52-24 win over Ohio State.[9] Following the national title game, Barmore announced that he would forgo his remaining two years of eligibility and enter the 2021 NFL draft.[8]
Barmore was selected by the New England Patriots in the second round (38th overall) of the 2021 NFL draft.[12] Barmore was the first defensive tackle selected. He signed his four-year rookie contract, worth $8.5 million, on July 21, 2021.[13] He played in all 17 games and was named to the PFWA All-Rookie Team.[14]
On November 18, 2022, Barmore was placed on injured reserve.[15] He was activated on December 17.[16]
On April 29, 2024, Barmore signed a four-year contract extension with the Patriots worth up to $92 million.[17] This made him the highest paid player in New England Patriots history, not named Tom Brady.[18] On July 28, Barmore was diagnosed with blood clots, rendering him out indefinitely.[19] He was placed on the reserve/non-football injury list to begin the season.[20] He was activated on November 16.[21]