Kuchar was flawless on day three, posting four birdies without dropping a shot, to be the 54-hole leader at 18 under.
Kuchar has made only one bogey through 54 holes at Waialae Country Club, and his 18-under 192 was the lowest 54-hole score of his career.
However, Putnam handed back the initiative with a scrappy dropped shot at 14, and Kuchar seized his chance to open up a commanding lead when he holed back-to-back birdie putts from 12 feet at 15 and 16.
Clearly, the 40-year-old is in a better spot than when he had gone more than three years without winning and was left off the Ryder Cup team for the first time in 10 years.
"Honestly, I didn't think about it at all until after the third one went in", Reavie added.
This time, he wouldn't let go, with three birdies over his final four holes to emphatically seal a four-shot victory.
It was only the second time Kuchar has won twice in the same season.
I love golf. Grade: A+.
"I want to see how great this year can be", Kuchar said.
Roger Sloan of Merritt, B.C., (72) finished 8-under, Adam Svensson of Surrey, B.C., (68) was 7-under, Adam Hadwin of Abbotsford, B.C., (67) came in 5-under while Mackenzie Hughes of Dundas, Ont., was 1-over through three rounds and didn't play the final day.
Kuchar, who had been winless for almost four years until his win at the Mayakoba Classic late in 2018 now appears likely to add a 9th PGA Tour title just three months after his 8th. He's a victor again, and for a guy who loves Hawaii, he was thrilled to already have a spot reserved at Kapalua for the winners-only field 50 weeks from now. Obviously a year ago was disappointing, but to win two out of three events is insane to comprehend. He has been to five of the islands, and plans to stay another few weeks after the Sony Open.
Kuchar, who is chasing his first win since November, carded a 4-under 66 Saturday at the Waiʻalae Country Club in Honolulu, Hawaii.
Andrew Putnam took the lead over Kuchar as the two began their third round as the one-time PGA Tour victor impressed.
Australia's Marc Leishman finished in a four-way tie for third place at 17 under with Canada's Corey Conners and Americans Hudson Swafford and Chez Reavie. But the veteran steadied himself down the stretch, racing past Putnam with a flurry of four birdies in seven holes on the back nine.