Fuller was an accomplished student-athlete at Ohio State and was named the school's 22nd NFF Scholar-Athlete and earned Academic All-America accolades three times. On the field, he recorded 224 career tackles, led the team in 2018, was second in tackles in 2017, and third in tackles his final year in 2019. Fuller also hauled in five interceptions, with two against Michigan, along with 10 passes defensed. He was a First-team All-Big Ten safety as a senior when he recorded 62 tackles, two interceptions and four pass break-ups. He finished the 2019 season as a semifinalist for the Jason Witten Man of the Year award, the Lott IMPACT Trophy and the William V. Campbell Trophy. As a junior, he was named second-team All Big Ten by the league's coaches and media after registering 81 tackles, an interception and two fumble recoveries. He played in 53 games (43 starts) during his collegiate career and was voted a team captain in 2018 and 2019.
Fuller grew up in Norwood, New Jersey and attended Northern Valley Regional High School at Old Tappan. He played multiple positions for the Golden Knights and was named the Gatorade Player of the Year for New Jersey and the State Player of the Year by NJ.com. As a senior, he rushed for 747 yards and 10 touchdowns, caught 33 passes for 886 yards and five TDs, and made 44 tackles and intercepted six passes on defense. Fuller played in the U.S. Army All-American Bowl. He is son of Bart Fuller and Cindy Mizelle, who is a professional singer that performed with Bruce Springsteen, the Rolling Stones, Whitney Houston, Luther Vandross and others. His brother, Devin, played football collegiately at UCLA and spent a season with the Atlanta Falcons and he has one sister, Jasmine. Following the Rams' Super Bowl victory, Fuller returned to Columbus for his college graduation after earning his degree in business administration.