In his senior season with Nebraska he was awarded the Heisman Trophy, given to the best individual player in college football. His first professional experience was with the Pittsburgh Maulers, a single-season (1984) franchise in the springtime United States Football League. In 1985, he played for the Jacksonville Bulls of the USFL and rushed for 1320 yards. When the Bulls and eventually the USFL as a whole folded, Rozier was free to pursue a career in the National Football League, which he did, primarily with the Houston Oilers, but never seemed to fulfill the tremendous potential that he had displayed in college.
Many pundits thought at the time that he would become one of the best running backs in history. Some have speculated that Rozier never fully recovered from an ankle injury suffered in his last collegiate game, the famous 1984 Orange Bowl in which Miami defeated Nebraska 31-30. Rozier had 138 yards on 21 carries at halftime against a Miami defense that was one of the best in the country, but he had to leave in the third quarter following the injury. Rozier finished the game with 147 yards on 26 carries.
In 8 seasons in the NFL, Rozier rushed for 4462 yards and 30 touchdowns. His best season came in 1988 with Houston when he rushed for 1002 yards and 10 touchdowns. He was elected to the College Football Hall of Fame in 2006.