The 24-year-old Californian showcased his world-class iron play down the stretch in making five birdies in his last seven holes to overtake a fading Rory McIlroy and win the DP World Tour Championship with a final-round 6-under 66 on Sunday.
With the 3-shot victory, Morikawa sealed the Race to Dubai title as the leading points winner on the European Tour.
Matt Fitzpatrick, the 2020 winner of the World Tour Championship and one of five players who started the week with a chance to overtake Morikawa in the Race to Dubai standings, launched a stunning final-day attack from 13th place after the third round.