Campbell played college football for the Texas Longhorns, where he won the Heisman Trophy and earned unanimous All-American honors in his senior season, as well as numerous other accolades.

Campbell won the AP NFL Most Valuable Player Award in 1979 after leading the league in rushing yards and touchdowns.

With head coach Bum Phillips, Campbell's emergence in Houston coincided with the Luv Ya Blue era, a period of sustained success in which the Oilers made three straight playoff appearances.

That season, Campbell was named Mr. Football USA as he was adjudged the national high school player of the year.

In the third game of the season, against the Rice Owls, Campbell scored four touchdowns during a 72–15 blowout in which Texas kicker Russell Erxleben set an NCAA record with a 67-yard field goal.

[13] In his final regular-season game, Campbell rushed for a career-high 222 yards in a 57–28 victory over rival Texas A&M, and the Longhorns finished the regular season undefeated.

Campbell carried 29 times for 116 yards in the game, but Notre Dame was victorious, 38–10, and claimed the national championship.

[15] The Sporting News and United Press International each named Campbell the college football player of the year.

[27] With quarterback Dan Pastorini nursing a mid-season shoulder injury, Campbell carried the Oilers to a five-game winning streak in 1979, which concluded with a 30–24 victory over the Dallas Cowboys on Thanksgiving Day, in which he rushed for 195 yards and two touchdowns.

"[34] Pittsburgh Steelers running back Franco Harris said, "Knocking over people can look very good but you can't do it forever.

"[34] After an 11–5 regular-season record in 1979, the Oilers defeated the Denver Broncos in the wild-card round for their first home playoff win since 1960.

[39] Campbell also threw a 57-yard touchdown pass to receiver Billy "White Shoes" Johnson against the Steelers for his only career completion out of three attempts.

[37] Bum Phillips was fired three days after Houston's loss in the wild-card game, and defensive coordinator Ed Biles was given the head coaching job.

[48] After rushing for 278 yards total in the first six games of 1984, Campbell was traded to the New Orleans Saints, reuniting him with Bum Phillips.

[49] The Saints received Campbell in exchange for their first-round draft pick in 1985,[50] with which Houston selected cornerback Richard Johnson.

[51] In his first game with New Orleans, Campbell carried five times for 19 yards, and continued to have a diminished role in the offense throughout the rest of the season.

Campbell is widely acknowledged as one of the best power running backs in NFL history,[57][58] and was highly regarded by his peers.

[34] Cornerback Lester Hayes of the Raiders said, "Earl Campbell was put on this earth to play football.

"[59] Cliff Harris, safety for the Cowboys, recalled Campbell as "the hardest-hitting running back I ever played against.

"[60] Campbell is considered one of the greatest running backs in Texas Longhorns and college football history.

[18][61][62] He was inducted into the College Football Hall of Fame in 1990, along with fellow Heisman winner Jim Plunkett of Stanford.

In 2010, NFL Network ranked Campbell the 55th greatest player of all time in The Top 100: NFL's Greatest Players,[71] and he was ranked by the sportswriter Max Bertellotti of the Turner Sports Network as the number 3 "power back" of all time, behind Jim Brown and John Riggins.

[73] The same year, he was featured on the cover of Dave Campbell's Texas Football, an honor that eluded him during his playing days.

Campbell was declared an official State Hero in 1981 by the Texas legislature, an honor previously bestowed upon only Stephen F. Austin, Sam Houston and Davy Crockett.

[75] A section of roadway in Tyler, Texas, extending from Loop 323 to SH155 was named the Earl Campbell Parkway at its opening in 2012.

[80] Tyler was a running back for Pasadena City College and San Diego State[81] but was forced to give up the sport due to multiple sclerosis (MS).

[82] He returned to Texas after graduation and divides his time between the family business and raising awareness of MS with his father.

[86] As of 2016, he still actively participated in University of Texas athletics, serving as special assistant to the football team.

[88] He developed foot drop due to nerve damage in his legs, and has difficulty bending his back and knees.

"[83][93] In 2009, Campbell became addicted to painkillers prescribed for his spinal stenosis, taking as many as ten OxyContin pills a day with Budweiser.