The Wildcats, 0-5 this season with another possible game next week, are on a record 12-game losing streak after dropping their final seven games in 2019. The 70 points they allowed Friday night marked the most ever surrendered in Territorial Cup series history, dating to 1899.
"When we hired Kevin three years ago, we had very high hopes for our football program," Arizona athletic director Dave Heeke said in a statement. "Unfortunately, we simply have not seen the results and upward trajectory in our program that we needed to, and I believe now is the time for a change in leadership. I thank Kevin for his service to the University of Arizona and wish him the very best in the future."
Sumlin had two years left on his contract. Heeke said the school will honor the terms of Sumlin's existing deal, including a $7.5 million buyout.
Arizona went 9-20 -- 6-17 in the Pac-12 -- with no bowl appearances under Sumlin, and it lost all three games to Arizona State. The lopsided Territorial Cup defeat comes two years after the Wildcats blew a 19-point fourth-quarter lead in a 41-40 loss.
Sumlin, 56, went to Arizona from Texas A&M, where he went 51-26 but finished no higher than fourth in the SEC West Division in his final five seasons. He replaced Rich Rodriguez, who guided Arizona to a Pac-12 South Division title and five winning seasons out of six.
"Our attention now turns to finding the next head coach at the University of Arizona, while we continue to support our student-athletes, who have sacrificed so much since returning to campus this summer," Heeke said. "We will cast a wide net to identify and recruit a coach who shares our vision, our values and our passion for winning."
Defensive coordinator Paul Rhoads, the former coach at Iowa State, will serve as Arizona's interim coach for a possible sixth game next week.
Potential head-coaching candidates for Arizona include senior defensive analyst and former Wildcats All-America safety Chuck Cecil, Nevada coach Jay Norvell, BYU coach Kalani Sitake, Navy coach Ken Niumatalolo, San Jose State coach Brent Brennan, NC State offensive coordinator Tim Beck, New Orleans Saints defensive line coach Ryan Nielsen, Weber State coach Jay Hill, Fresno State coach Kalen DeBoer and former UCLA coach Jim Mora.
Niumatalolo was a finalist for the job in 2017 before Arizona pivoted to Sumlin.
Sumlin made a name for himself in four years at Houston, leading the Cougars to an 11-2 record and a Cotton Bowl win in 2012. He got off to a good start at Texas A&M, leading the Aggies to five straight bowl games. The Aggies tailed off after winning 20 combined games in Sumlin's first two seasons, however, and he was fired after a 7-6 season in 2017.
After showing some early promise, Arizona went on a downward spiral, capped with a record loss to its biggest rival.
"It's what we sign up for, right?" Sumlin said after the Arizona State loss. "It's a tough deal.''
The embarrassing loss led numerous former Arizona players, many of whom played under Sumlin, to call for his firing on social media.
"Just fire everyone please,'' former Arizona quarterback Matt Scott tweeted. "This product we're putting on the field is hard to watch.''
The Associated Press contributed to this report.