Del Rio's job security had been tenuous since owner Wayne Weaver said the coach needed to make the playoffs to secure a 10th season in Jacksonville. The Jaguars were essentially eliminated with Sunday's 20-13 loss to Houston.
The Jaguars are struggling to sell tickets and host a Monday night game against San Diego.
Del Rio leaves with a 69-73 record, including 1-2 in two playoffs appearances. The Jaguars didn't win the AFC South in any of his nine seasons.
Weaver considered firing Del Rio after last season, but kept him partly because of the uncertainty surrounding the NFL lockout.
Del Rio, a Mexican-American who played football and baseball at USC, spent 11 years in the NFL as a linebacker for the New Orleans Saints, Kansas City Chiefs, Dallas Cowboys, Minnesota Vikings and the Miami Dolphins. He retired in 1996 and began his coaching career with the Saints in 1997 as a strength and conditioning coach.
He took over a Jaguar's head coach in 2003, after the dismissal of Tom Coughlin.
Besides his playing and coaching career, Del Rio is known as the second NFL coach since 1993 to wear a suit on the sidelines. Del Rio wore the suit a day after then-San Francisco 49er's head coach Mike Nolan wore one in November of 2006.
Based on reporting by the Associated Press.