He was a Fred Biletnikoff Award preseason watchlist honoree in 2010, and set Michigan's single-game receiving record with nine catches for 246 yards against Illinois that November.

[2] With the dismal academic situation and a mediocre athletic program, Belmont left Roundtree dissatisfied, and he transferred to Trotwood before his junior year, where coach Douglass had earned a reputation for developing college ready football players, and where former Flames teammate Domonick Britt was playing quarterback.

[6] As a senior, he was selected to the Division II first-team all-state squad, and named Ohio's offensive player of the year.

He was also chosen to play in the Big 33 Football Classic,[3] and ranked as the number 44, 89, and 104 wide receiver in the nation by Rivals.com, Scout.com, and ESPN, respectively.

[4][7][8] In that same year, Trotwood won their first playoff game since 1981, led by Roundtree's 13 receptions, 203 yards, and game-winning touchdown.

[3] Roundtree made the 2010 preseason watchlist for the Biletnikoff Award, which honors the nation's top wide receiver.

[23][24] At the midpoint of Michigan's 12-game regular season schedule, he ranked fifth in the Big Ten in receptions per game, and seventh in receiving yards.

[28] The performance raised him to fourth in the conference in both yards and receptions (tied) per game,[29] and earned him Co-Big Ten Offensive Player of the Week honors.

[43] Roundtree followed Junior Hemingway as the second person to wear Desmond Howard's "Michigan Football Legend" jersey number 21.

[45] Playing in his final game at Michigan Stadium, a 42–17 victory over Iowa, Roundtree caught five passes for 83 yards and a touchdown.

[47][48] He posted his four highest receiving yardage totals of the season after Devin Gardner replaced Denard Robinson at quarterback.

[50] Following the season, Roundtree participated in the January 19, 2013 Raycom College Football All-Star Classic, making a 39-yard catch and returning 2 punts.

[54] Roundtree made his professional debut on March 15, 2015, catching 3 touchdowns, during a 59–40 loss to the Sioux Falls Storm.