In a statement posted on its website, the school said Howland, 55, has been relieved of his duties "effective immediately and a national search for his successor has begun."
The statement said Director of Athletics Dan Guerrero notified Howland of the change Sunday afternoon.
"I want to thank Ben for all that he has done for UCLA in his 10 seasons in Westwood," Guerrero said. "He embraced our tradition and culture and produced some terrific teams and coached a number of wonderful young men. We wish Ben and his family all the best as they move onto a new chapter in their lives."
Howland's UCLA teams went 233-107 and reached the NCAA Tournament seven times -- advancing to the Final Four in three straight seasons from 2006-08 -- but never won an NCAA title.
The Bruins were eliminated in the second round of this season's NCAA tournament, falling to Minnesota 86-66.
As a head coach at Northern Arizona, Pittsburgh and UCLA, Howland's career record is 390-199.
"The UCLA community and fans have been unbelievable to my family and I, and it's been an honor and privilege to represent this great institution," Howland said in a statement. "I look forward to what comes next."