With hardly a breath of wind on a glorious day of unbroken sunshine at Riviera Country Club, the 34-year-old American fired a flawless seven-under-par 64 to take control of the PGA Tour event.
Kuchar made a sizzling start with birdies on his first three holes and picked up four more shots to finish two ahead of compatriot Brandt Jobe, who is playing the tour on a medical exemption this year due to a herniated disc.
Briton David Lynn and American rookie James Hahn opened with 67s while Riviera fan favourite Fred Couples, a twice champion who is competing in the event for a record 31st time, was among a group of seven players knotted on 68.
Among those at three under were British world number eight Lee Westwood, American veteran Jim Furyk and Swede Fredrik Jacobson.
Kuchar, who has a surprisingly low-key record at Riviera where he has always relished playing, was delighted with his opening round.
"It was a great day," the four-times PGA Tour winner, who has spent the last three weeks in Palm Springs and Hawaii on a family holiday, told reporters with a smile.
"It's always fun to have bogey-free days, especially around this golf course. I got off to a great start, birdied my first three and all three were kick-in birdies, all within probably four feet.
"Just drove it well today which is a big key around here. The greens are pretty tricky and pretty firm this year so coming out of the rough, it's difficult to get a ball to stop close to the hole."
Asked to explain his relatively poor record at Riviera where he has recorded just one top-15 finish in his previous seven starts, Kuchar replied: "Not real sure ... but it's one of those places where every time I come, I enjoy myself here."
Twice champion Phil Mickelson, who clinched his 41st PGA Tour title at the Phoenix Open two weeks ago, offset four birdies with four bogeys to start out with a level-par 71.
"It could have been better but it could have been a lot worse, and I'll certainly take it," the American left-hander said after bogeying his penultimate hole, the par-four eighth.
"I hit the ball pretty solid (in practice) yesterday. I felt like I was on the right track, and when I came out this morning, it was a little bit off.
"I was hitting some pull-hooks, I was hitting some block cuts and so I put myself in some not great spots off the tee. Had to fight to make pars and I'm pretty fortunate, I think, to shoot even par."
Fellow American Bill Haas, who played in the same group with Mickelson, launched his title defence with a 70 while Masters champion Bubba Watson struggled to a six-bogey 77.
British world number three Luke Donald and seventh-ranked Australian Adam Scott were among the late starters.
- Sports & Recreation
- Riviera Country Club