In his freshman season with the Yellow Jackets, Marshall was placed in the A-back position as part of head coachPaul Johnson's triple option.[4][5] In his first game with the Jackets, a 69–6 win against Alcorn State, Marshall rushed for 18 yards on one carry and caught a pass for 24 yards.[5] In total, Marshall played in 9 games in his freshman season, with eight carries for 58 yards and 3 passes for 76 yards.[2]
Marshall served as the 3rd string quarterback for the 2016 season, throwing one completion in two attempts and taking 14 snaps.[6] He appeared in 2 games.[2]
Prior to the first game of the season, Johnson announced that Marshall would be the Jackets' starting quarterback, replacing Justin Thomas, who had graduated following the 2016 season.[6] Marshall made his debut as Tech's starting quarterback at the 2017 Chick-fil-A Kickoff Game.[4] In the game, a 42–41 double overtime loss to the Tennessee Volunteers, Marshall set multiple school and conference records in rushing. He broke Georgia Tech's record for rushing touchdowns in a single game (5) and broke the ACC record for most rushing yards by a quarterback in a single game (249).[7] Marshall ended the season with 1,146 rushing yards over 247 carries, 927 passing yards, and 27 total touchdowns.[2][8]
Entering into his senior season, Marshall was placed on the watchlist for the Maxwell Award alongside fellow Yellow Jacket KirVonte Benson.[9] In his final season with the Jackets, Marshall would start in six of the first seven games, with Tobias Oliver as a backup quarterback. Following an injury sustained in a game against the Duke Blue Devils, Marshall sat out the next game against the Virginia Tech Hokies, leaving Oliver to start.[10] Marshall would later be benched due to injuries during a game against the North Carolina Tar Heels.[11]