Casey Mears grabbed second place 12 laps from the end and gave a big effort to try to catch Kenseth, but the Roush Fenway Racing driver wouldn't let Mears get close enough for a serious challenge, driving across the finish line about five lengths ahead.
"It was really a lot of fun," said Kenseth, who earned his 22nd Busch victory in his 200th series start. "I owe a lot of this to my former teammates Mark Martin and Jeff Burton. I learned a lot about these tracks from them. And I'm real excited to get this team back where they belong."
Kenseth, giving Jack Roush his first win since he sold half his team to Fenway Sports Group earlier this month, took the lead with a pass of Burton, now driving for Richard Childress Racing, on lap 129.
The 2003 NASCAR Cup champion and winner of last February's Cup race here led the rest of the way. He wound up leading a race-high 48 of the 150 laps.
"I burnt my tires off pretty good just getting to the front," said Mears, who moved from Chip Ganassi Racing to Hendrick Motorsports over the winter. "After that, I didn't have much left. But I'm real happy with the effort by our whole team."
Kenseth's first three Busch wins in Robbie Reiser's car, but this one gives Roush his sixth victory in the last seven Busch races at California, including three wins by Greg Biffle, one by Carl Edwards, one by Martin and Saturday's night triumph by Kenseth.
"We just really like these big, fast racetracks and this one has been real good to us," Roush said, grinning.
Kyle Busch finished third, followed by Edwards, Biffle and Daytona winner Kevin Harvick, who made up a lap after a blown tire in the early going. Burton slipped to seventh at the finish.
Dave Blaney gave Toyota its first Busch Series pole, but wound up 10th in the race.
As usual, the Busch race was dominated by Nextel Cup regulars, with drivers who will run in Sunday's Auto Club 500 finishing in 15 of the top 16 positions. Only Regan Smith, who will run part-time in Cup this season, was able to break into that group, finishing ninth.
Juan Pablo Montoya's continuing stock car apprenticeship took a hit when he became the innocent victim in a hard crash on lap 87.
Jason Leffler was attempting to pass Kenny Wallace in a three-wide maneuver and appeared to move up the track too soon, making contact with Wallace. Leffler's car then turned abruptly toward the outside wall and hit it hard, collecting Montoya who was racing at the top of the banking.
Sam Hornish Jr., like Montoya a former Indianapolis 500 winner making the transition to NASCAR, also crashed out late in the race.