Kiffin's deal is believed to be for three years, with two one-year club options.
The Raiders announced the hiring on their Web site Monday evening and have scheduled a news conference for 1 p.m. today.
Kiffin, 31, agreed to succeed Art Shell on Monday, 18 days after managing general partner Al Davis fired Shell after the Raiders' 2-14 season. Kiffin is slightly more than half Shell's age (60) and younger than defensive tackle Warren Sapp, 34.
Not that Davis cares. He succeeded as the Raiders head coach in his early 30s, as did two coaches hired by Davis, John Madden and Jon Gruden.
Kiffin could not be reached for comment. Numerous calls to Raiders headquarters went unanswered.
Monday marked Kiffin's second face-to-face meeting with Davis in five days. They met Thursday, when USC assistant head coach/quarterbacks coach Steve Sarkisian still was a candidate to replace Shell. Kiffin came along as a potential candidate to replace offensive coordinators Tom Walsh and John Shoop.
Davis offered jobs to both Sarkisian and Kiffin on Friday. Both said no. Kiffin, though, later agreed to listen to Davis once the talks concerning him changed from offensive coordinator to head coach.
A person close to Kiffin said Kiffin arrived in Oakland intent upon taking the Raiders job, if offered.
After Sarkisian's second interview, he changed his mind and returned to a reported hefty raise at USC.
Kiffin, current Raiders defensive coordinator Rob Ryan and former New York Giants coach Jim Fassel were the lone candidates still in the running to replace Shell. Kiffin has spent the past two years as USC's offensive coordinator. He called the plays, while Sarkisian worked from the sideline as an adviser to coach Pete Carroll.
Kiffin interviewed for the University of Minnesota job that went to Tim Brewster earlier this month and also received a call from new Alabama coach Nick Saban about joining his staff, but he declined an interview.
Sarkisian has never called plays. He was the Raiders quarterbacks coach in 2004.
Kiffin's NFL experience is limited to one season. He worked with the secondary as the defensive quality control coach for the Jacksonville Jaguars in 2000 before he arrived at USC.
Kiffin's father, Monte, is the longtime Tampa Bay Buccaneers defensive coordinator.
One of Kiffin's first duties will be hiring an offensive coordinator. Davis interviewed former Raiders offensive coordinator Marc Trestman for the vacancy two weeks ago.
Kiffin's multiyear deal is similar to the one signed by Gruden in 1998. The Raiders picked up the first of Gruden's two options but traded him after the 2001 season to the Buccaneers.
Meanwhile, FoxSports.com, attributing unnamed "NFL sources," reported that the Raiders are exploring a trade with Atlanta that would send quarterback Michael Vick and the Falcons' first-round draft pick (No.10 overall) to the Raiders for wide receivers Randy Moss and Jerry Porter and the No. 1 overall pick in the 2007 NFL draft. Raiders senior personnel executive Michael Lombardi didn't respond to a request for a comment about the report.