As a star halfback playing college football for the Ohio State Buckeyes, Warfield was twice named to the all-conference team in the Big Ten.

[5] He also ran track and field at Warren G. Harding, and was the Ohio High School Athletic Association Class AA broad jump champion in 1958.

As the secondary ball-carrier behind fullback Bob Ferguson during Ohio State's national championship season in 1961, Warfield carried 77 times for 420 yards and five touchdowns.

[9][10] A two-time letterman in track and field at Ohio State, Warfield competed as a broad jumper, hurdler, and sprinter.

He excelled as a broad jumper, recording a personal best of 26 feet 2 inches, and was an Olympic prospect before he decided to play professional football.

But during workouts prior to the season, his play as a wide receiver impressed head coach Blanton Collier, and he was converted to the position.

He averaged 17.8 yards per reception, and his speed served to complement the power of star running back Jim Brown.

[14][15] The Browns finished the season atop the East Division with a 10–3–1 record, and defeated the Baltimore Colts 27–0 in the 1964 NFL Championship Game.

[18] The Browns returned to the NFL Championship Game in 1965, in which Warfield caught two passes for 30 yards in a 23–12 loss to the Green Bay Packers.

[17] After another NFL championship game appearance for the Browns and Pro Bowl season for Warfield in 1969, he was traded to the Miami Dolphins for the third pick in the 1970 draft.

The trade is considered one of the most lopsided in NFL history, as Phipps had only limited success for the Browns, while Warfield was a major factor in the Dolphins' championships in the early 1970s.

[27] In need of a deep-play receiver, Dolphins head coach Don Shula stated he "jumped at the chance" to acquire Warfield, saying he had always admired him and called him "a real thoroughbred, equal to the best in the game.

[31][32] He earned first-team All-Pro honors from the AP and UPI, among other selectors, and made his fourth consecutive Pro Bowl appearance.

[17] Through the Dolphins' first two games of the 1971 playoffs, against the Kansas City Chiefs and Baltimore Colts, Warfield caught nine passes for 265 yards and a touchdown.

[37] Warfield missed two games in the Dolphins' undefeated 1972 season due to an injured foot but still led the team with 606 receiving yards.

[44] Prior to the start of the 1974 season, Warfield and teammates Larry Csonka and Jim Kiick made what were then surprising decisions.

They left the Dolphins at the conclusion of the season for what appeared to be more lucrative pastures with the Northmen of World Football League (WFL).

[47] After the dissolution of the WFL following the 1975 season, Warfield told reporters he would be interested in rejoining the Browns if the Southmen were not admitted into the NFL.

[54] Warfield was inducted into the Pro Football Hall of Fame in 1983, his first year of eligibility, one of only five Dolphins to accomplish this feat (Jim Langer, Jason Taylor, Dan Marino and Don Shula).