He attended the 2015 Senior Bowl, as the first NCAA Division III player picked to play in the all-star game in 25 years.

Sports Illustrated named Marpet the "biggest riser" at the game, and included him on its All-Offense team.

At the Scouting Combine in February 2015, he ran the fastest 40-yard dash among offensive line prospects eligible for the 2015 NFL Draft (4.98), the fastest 10-yard (9.1 m) split (1.74 seconds), and also the second-best time in the three-cone drill (7.33) and 20-yard shuttle (4.47), while scoring the highest "Speed, Power, Agility, Reaction and Quickness" (SPARQ) score.

[15] At Hastings High School, Marpet played offensive tackle and defensive end for the Yellowjackets, was a three-time varsity letterman, named second-team All-State, earned all-section honors, and was a two-time all-league selection.

[17] Marpet quit playing football after his freshman year to focus on basketball where he earned all-league selection twice.

[6][16] Marpet rejoined the football team in his junior year, by which time he weighed 210 pounds (95 kg).

[2][18][19] Hobart is a small private liberal arts college of 2,271 students in Geneva, in Upstate New York.

Marpet started 37 of the 43 games he played, helping the Statesmen win four consecutive Liberty League Championships.

[25][26] Marpet and the Statesmen made four consecutive NCAA Division III Football Championship appearances, advancing to the quarterfinal rounds in 2012 and 2014.

[4][16][28] He started all 11 games during the season and was All-Liberty League first-team, Liberty League All-Academic, Jewish Sports Review All-American, D3football.com All-East second-team, Eastern College Athletic Conference (ECAC) North All-Star second-team, and won the Tryon Football Award.

[27] He was one of the only linemen who was able to block University of Washington defensive tackle and first round pick Danny Shelton.

[35] Sports Illustrated named Marpet the "biggest riser" at the Senior Bowl, and included him on its All-Offense team.

[44] CBS Sports wrote that Marpet was a "quick thinker with a high football IQ, with NFL toughness and play speed".

[60][61] He started 11 games at center before being placed on injured reserve on November 29, 2017, with a knee injury, and played 723 snaps on the season.

[64] During the 2018 offseason, head coach Dirk Koetter said that Marpet would be moved back to left guard after the team signed former Ravens' starting center Ryan Jensen.

[74] Marpet played in all four games in the Buccaneers' playoff run that resulted in the team winning Super Bowl LV.

[77] On February 27, 2022, Marpet announced his retirement from professional football at age 28 after seven seasons via an Instagram post.

Many former teammates, including Tom Brady, wished Marpet congratulations on his retirement via various social media platforms.