Purnell has gone 94-67 in his five years with Clemson and has a school-record 49 wins during the past two seasons.
The Tigers made the NCAA tournament for the first time since 1998 and will open against Villanova on Friday night. Clemson finished third in the Atlantic Coast Conference, its best finish since winning the regular-season title in 1990.
"Oliver Purnell has built this program the right way, and we are now well respected in the ACC and nationally," Clemson athletic director Terry Don Phillips said. "We have made a strong commitment to build upon what he has established in the last five years."
Purnell will get a raise to move him into the top third in pay among ACC coaches, Phillips said.
The exact terms of the deal will be released later, officials said.
"It's a happy day for me," said Purnell, a former Maryland assistant coach. "I've coached at a lot of outstanding programs, Old Dominion and Dayton just to name a couple, that were committed to basketball -- great places. The commitment that is here is stronger than I have ever felt before. This feels like home."
Senior James Mays was part of Purnell's first full recruiting class. Clemson went 16-16 and 5-11 in the ACC in Mays' freshman season, 2004-05.
"I'm really happy for him," Mays said. "He really deserved it. He brought this team a long way from where we were to where we are now."
Purnell said Clemson has had the things needed for long-term success with other coaches but lacked one ingredient the school now has.
"I think stability is very important in a basketball program," Purnell said. "We have the opportunity to have that here."
UCLA -- Kevin Love and Luc Richard Mbah a Moute are on the mend from injuries suffered in last weekend's Pacific-10 tournament, although coach Ben Howland was vague on whether Mbah a Moute would play in tomorrow's NCAA tournament opener against 16th-seeded Mississippi Valley State. Love, the Pac-10 player and freshman of the year, strained his lower back in the opening minute of Saturday's title game against Stanford. Love is receiving treatment for the injury, but he was not limited in practice yesterday. "He seemed to be in good spirits," Howland said. "He might have been a little sore." The center is expected to start tomorrow. Mbah a Moute sprained his left ankle for the second time this season in Friday's Pac-10 tourney semifinal win over Southern California and didn't play in the title game. The junior forward, a veteran of consecutive Final Four appearances, was off crutches and in a walking boot Sunday.
San Diego -- Coach Bill Grier has agreed to a contract extension after leading the Toreros to the NCAA tournament in his first season. Terms of the extension weren't announced. Grier, a longtime assistant at Gonzaga, was hired last March after Brad Holland was fired.
Et cetera -- Sonny Weems, Arkansas' leading scorer, hurt his knee at practice but is not expected to miss the Razorbacks' first-round NCAA tournament game against Indiana on Friday. ... Former LSU coach John Brady has emerged as a strong candidate for the Arkansas State job. Brady was fired by LSU on Feb. 8, less than two seasons after leading the Tigers to the Final Four. ... Idaho fired coach George Pfeifer after two seasons and a 12-48 record.