Cavendish, a 25-time Tour de France stage winner, raced to his 10th victory of the season, finishing the 126.2-mile flat road race in 4 hours 43 minutes 27 seconds. He also won Tour of California stages in Sacramento in 2010 and last year, also on the opening day.
“I thought (teammate)
Sagan, the four-time sprint competition winner in the Tour de France and an 11-time stage winner at the Tour of California, was second in the same time.
Jean-Pierre Drucker of Luxembourg was third in the mass sprint, also in the same time.
"The team had confidence in me and I gave them back with a result," Drucker said. "I am maybe not the fastest sprinter, but I can still do some good placement and get some good results. So I will try to be up there again tomorrow."
The second stage Monday is a 120-mile road race from Nevada City to Lodi.
Cavendish, who claimed his sixth career win in the Tour of California, waited behind Renshaw while Sagan moved to the front just after the final corner and with about 600 yards left.
"I didn't have to think about it," Cavendish said. "I just followed."
Four riders built nearly seven-minute after breaking from the starting field of 143 in the opening miles of the stage. The foursome was reduced to a twosome as the leaders approached finishing circuits around the State Capitol. The leaders were caught just crossing the finish line on the first of three two-mile concluding circuits.