Mathis played
college football for the
North Dakota State Bison from 2018 to 2023. He played in one game in 2018, but did not record a catch, and was
redshirted. He played in 12 games, starting two, during the fall 2021 season, recording eight receptions for 112 yards. Mathis played in all 15 games, starting 10, in 2022, totaling 35 receptions for 520 yards and three touchdowns. He caught seven passes for 123 yards in the
national championship game loss to
South Dakota State. Mathis was also named to the
Missouri Valley Football Conference Honor Roll that season. He appeared in all 15 games, starting 13 games, in 2023, catching 46 catches for 665 yards and six touchdowns. He led the Bison in receptions and receiving touchdowns while finishing second in receiving yards. Mathis was also one of six team captains that season. ==Professional career==