Ian Poulter, of England, hits from the 15th fairway during the final round of The Players Championship golf tournament Sunday, May 14, 2017, in Ponte Vedra Beach, Fla.
"He played like someone that was doing it for five or six years, like it was just another round of golf", said Louis Oosthuizen, who played the final round with Kim and finished in a tie for second with Ian Poulter. He now has a five year exemption on the PGA Tour, a three-year exemption to The Masters and a cheque for $1,890,000.
Elsewhere at Sawgrass on Sunday there was drama as Rafa Cabrera Bello scored a rare albatross.
Kim started Sunday's final round in fourth place, two shots behind overnight leaders JB Holmes and Kyle Stanley.
Kim's countryman, 30-year-old San Moon Bae, a three-time United States tour victor, is now completing his military service after losing a court case to defer it.
Kim eclipsed Adam Scott, who won the Players Championship at 23 in 2004.
He finished three strokes behind South Korea's Si Woo Kim and showed the fighting quality that has made him so popular with fans around the world.
He had already notched a maiden USA tour win at last year's Wyndham Championship.
Kim smashed Scott's record as youngest Players Championship victor, which the Queenslander set in 2004 aged 23 years, 8 months and 12 days.
Kim followed in the footsteps of South Korean K.J. Choi, who won the 2011 Players Championship and was all too happy to provide his countryman some tips about his experience.
Ahead of the tournament, Kim was 500/1 as he saw off the star-studded field at Ponte Vedra Beach to become the youngest Asian two-time PGA Tour victor, with the person - who wishes to remain anonymous - sticking on €100 each way.
He became the third global Players champion in four years and led seven worldwide players among the top-10.
A month ago he appeared to have lost his PGA Tour after not making enough prizemoney from his limited starts coming back onto the Tour with a medical exemption.
It has been a tough period for the Ryder Cup legend as injury robbed him of a few months of action last season, but he is determined to rediscover his top form. From a playing perspective to be in this situation where I can play a schedule and enjoy some golf, some of my best golf has come out this week. He tied for 41st, the worst finish by a 54-hole leader in tournament history.
Rory McIlroy struggled with both his new equipment and a pain in his back to a three-over 75, but both World No.1 Dustin Johnson and Hideki Matsuyama had impressive final rounds, with DJ's 68 leaving him in T12 and Matusyama's 69 putting him T22.