Bigsby took over as Auburn's starting running back his freshman year in 2020.[7][8] He had his first 100-yard game against Georgia, rushing for 146 yards on 20 carries.[9][10] Bigsby finished the season averaging 6.0 yards per carry for a total of 834 yards and was voted the SEC Newcomer/Freshman of the Year.[11][12] In 2021, Bigsby improved upon his strong freshman season and would rush for 1,099 yards and ten touchdowns.[13] In the 2022 season, he had 179 carries for 970 rushing yards and ten rushing touchdowns.[14]
Bigsby was drafted by the Jacksonville Jaguars in the third round, 88th overall, of the 2023 NFL draft.[17] In Week 1, he scored his first NFL touchdown in his NFL debut on a one-yard carry in the fourth quarter of a 31–21 victory over the Indianapolis Colts.[18] He appeared in all 17 games as a rookie. He finished with 50 carries for 132 yards and two touchdowns in the 2023 season.[19]
In Week 5 of the 2024 season against the Colts, Bigsby had 13 carries for 101 rushing yards and two rushing touchdowns in the 37–34 win.[20] In a Week 7 win over the Patriots, he had 26 carries for 118 rushing yards and two rushing touchdowns.[21]