Owner Wayne Weaver confirmed Del Rio's dismissal at a news conference, then added a couple of other big items to the day's agenda. He also said that general manager Gene Smith's contract has been extended for three years and also announced the sale of the team to Illinois businessman Shahid Khan.
The Jaguars are 3-8 this season, Del Rio's ninth at the helm, and are guaranteed a non-winning mark for the fourth straight year.
Del Rio has guided the club to a record of 68-71 since becoming the second head coach in franchise history after Tom Coughlin was fired following the 2002 campaign.
"I felt it was unfair to leave Jack twisting in the wind," said Weaver on Tuesday. "I told Jack I appreciated the nine years, but I think we deserve better, the community deserves better. We've been average over the past nine years. I take some responsibility in that. This team is not far from being a very competitive football team."
Defensive coordinator Mel Tucker will take over on an interim basis for the remaining five games of the season. Tucker is in his third season in charge of the team's defense, which ranks fourth in the NFL this season.
"I think Mel has been one of the bright spots of our football team this year," Weaver added. "I thought Mel earned the opportunity to be the interim coach to see us through. We're going to start an extensive coaching search to bring someone in who can help us become a winning franchise."
Weaver indicated that Tucker will be considered for the full-time position.
As for extending Smith's contract, Weaver said it will "give us the kind of stability we need in the football office with this change taking place."
Smith has been with the franchise since its inception in 1994, serving in a variety of roles from scout to personnel, and was elevated to his current position after the 2008 season when James Harris resigned. Harris had been in charge of the football operations since 2003 when Del Rio was also brought aboard.
The Jaguars had just three winning seasons during Del Rio's tenure and reached the playoffs as a wild card in 2005 and 2007, posting a 1-2 mark in the postseason.
Jacksonville's lone playoff win under Del Rio came after the 2007 season with a surprising triumph in Pittsburgh. A five-year contract extension soon followed, but so did a 5-11 season in 2008.
After a 7-9 mark in 2009, there was speculation that Del Rio was considering the vacant position at his alma mater, Southern California. He stayed with the Jaguars and the team went 8-8 in 2010.
Weaver then indicated that the Jaguars had to make the playoffs this year for Del Rio to keep his job.
Just days before the start of the season, Del Rio decided to release veteran quarterback David Garrard. It wasn't the first time Del Rio had made a controversial quarterback decision, as Garrard replaced Byron Leftwich under similar circumstances before the start of the 2007 season.
Luke McCown got the starting nod for this season's opener against Tennessee and the Jaguars came away with a 16-14 win, but things went downhill quickly and Del Rio turned to rookie Blaine Gabbert, who has had his ups and downs this year and was benched during this past Sunday's loss to Houston.
Del Rio had indicated on Monday that Gabbert would remain the starter. Tucker will now decide who starts for Monday's game against San Diego.
As for the decision to sell the franchise, Weaver said it was "bittersweet."
Weaver and his partners were awarded an expansion franchise by the NFL on November 30, 1993. It is the smallest market in the league.
The team began play in 1995 and reached the AFC Championship Game in just its second year of existence, losing to New England. In all, the Jaguars have made six playoff appearances under Weaver's ownership and the city was the host for Super Bowl XXXIX after the 2004 season.
There has been speculation that the franchise, which has struggled to sell out games, could be moved to a larger market, but Weaver believes the team will stay in north Florida.
"This team is going to be in Jacksonville for many years in the future," Weaver stated Tuesday. "That's my dream -- to see this team succeed in Jacksonville. We're a Jacksonville franchise and we plan to stay a Jacksonville franchise."
"He's passionate about football," Weaver said about Khan, who will likely be in Jacksonville for Monday's game. "He's keeping the Jaguars staff intact."
The team issued a statement from Khan following Weaver's news conference.
"Owning a team in the NFL has long been my personal and professional goal," Khan stated. "Becoming owner of the Jacksonville Jaguars would be a dream come true for me and my family, but above all, would be a privilege."
NFL owners must still approve the sale and Weaver indicated that the membership would likely vote on December 14 in Dallas.