With the University of Colorado's mascot Chip, student-athletes and top athletic officials in the audience, the CU regents on Friday morning unanimously approved the Boulder campus' move to the Pac-10.
CU becomes the first new member since the University of Arizona and Arizona State University were admitted in 1978.
"What a glorious day for the University of Colorado and the Pac-10," said Regent Tom Lucero.
CU will become a part of the West-Coast league beginning in fall 2012.
The Pac-10 will be the eighth athletic conference with which Colorado has been affiliated in its history.
Regent Jim Geddes said the school is proud to join the Pac-10, but does so with a sense of nostalgia as CU departs the Big 12.
"There have been so many great memories," Geddes said. "I'd like to thank our friends in the Big 12 for their tough competition."
He said the university is now excited to invade Pac-10 territory.
Regent Joe Neguse kept it short, thanking student-athletes and saying "Go Buffs!"
Regent Michael Carrigan said the Pac-10 is a good fit because CU belongs in a conference that's home to many of its alumni.
There are 35,595 CU alumni living in the Pac-10 states, according to the Alumni Association. That compares with 10,987 in the Big 12 states.
"I do hope Nebraska joins the Big Ten and I look forward to the Buffs beating Nebraska in the Rose Bowl," Carrigan said.