Sentry Tournament of Champions
Johnson began his final round with only a two-stroke advantage, but playing partner and closest challenger Brian Harman struggled to combat the wet and breezy conditions at Kapalua while the world No 1 matched the low round of the week, a superb seven-under 65 giving him a winning score of 24 under par.
Dustin Johnson was in imperious form as he cruised to an eight-shot win
The world No 1 looked focused and fully in control from the outset and gained complete control of the tournament with three birdies in four holes from the third before completing a flawless outward 32 with another birdie at the ninth.
He suffered his only blip at the tough 11th hole as he bunkered his tee shot and failed to get up and down, but his response on the next tee was astonishing as he came within six inches of making an albatross hole-in-one with a pure 433-yard drive.
The resulting tap-in for eagle was followed by a run of three consecutive birdies from the 14th, although he missed out on equalling David Duval’s record nine-shot win in 1999 when his 12-foot putt for his eight birdie of the round at the last slid past the target.
Johnson casually knocked in the return to cap his second victory in the tournament following his 2013 triumph, while Jon Rahm won the race for second as he closed with a 69 to finish on 16 under.
The Spanish sensation recovered from an opening bogey with three birdies over the next five holes and, after another blemish at the 13th, he birdied 14, 15 and 17 to pip Harman for outright second.
Harman effectively took himself out of contention with three bogeys over a scrappy, outward 37, and the left-hander did well to cut out the mistakes after the turn while picking up shots at 15 and 16 to salvage a 72 which ensured outright third ahead of Rickie Fowler, Hideki Matsuyama and Pat Perez.
Halfway leader Marc Leishman repaired the damage of his disappointing third-round 76 as a bogey-free 67 lifted him back into a tie for seventh on 13 under alongside Jhonattan Vegas, while Open champion Jordan Spieth fired a solid 69 to close one stroke further adrift.