Sellers attended Paxon High School where he excelled in football and basketball. He helped his team win the 1965 state basketball championship. He went on to star at Florida State University as a split end and flanker in Bill Peterson's pro-style offense. In 1967 and 1968 he received All-American honors. He recorded 212 passes for 3,598 yards and 23 touchdowns. He wore the number 34 which was retired by the school, until he gave linebackerErnie Sims permission to use it while playing for the Seminoles. Sellers still holds 17 receiving and scoring records at Florida State University- including single-season receptions, single-season receiving, single-game receptions, single-game receiving yards single-game receiving touchdowns. In 2007, he was named to The State of Florida’s “100 Greatest High School Football Players in Florida History”. In 1973, he was inducted into the Florida Sports Hall of Fame. In 1977 he was inducted into the Florida State University Hall of Fame. In 1988, he was inducted into the College Football Hall of Fame.
Sellers was selected by the Boston Patriots in the first round of the 1969 NFL Draft. He earned AFL All-Star honors as a rookie after making 27 receptions for 705 yards, with 6 touchdowns and 26.1 average yards per reception. In 1971, the team changed its name to the New England Patriots after relocating to Foxborough. During that season he missed four games due to injuries and lost his starting position. On July 13, 1972, he was traded to the Super Bowl championsthe Dallas Cowboys, in exchange for a third round draft choice.
Dallas Cowboys
In 1972 he was a backup until the seventh game, when he was promoted to replace Bob Hayes in the starting lineup, in order to take advantage of his big play ability. Even though he finished the season as the Cowboys top receiver, registering 31 receptions for 653 yards, five touchdowns and a 21.1 yards average per reception, the team looked to upgrade its receiving corps, by trading him along with a second round draft choice to the Super Bowl champions the Miami Dolphins, in exchange for Otto Stowe.
Miami Dolphins
In 1973, he had a disappointing season after playing in three games and catching only two passes. He was released on September 10, 1974.