In just under two-and-a-half years as a professional, he has won two Major Championships and a WGC title and can now add a Rolex Series victory and the Harry Vardon Trophy to his Wanamaker Trophy and Claret Jug.
He entered the season finale top of the Race to Dubai Rankings in Partnership with Rolex but had five players who could also take the title breathing down his neck.
The 24-year-old was safe in the knowledge that a victory would see him crowned European Number One and spoke throughout the week of keeping his focus on claiming a maiden Rolex Series victory and letting the rest take care of itself.
He teed off alongside closest rival Billy Horschel and set the tone on Thursday, carding a 68 which was six shots better than his countryman and stamping his authority on the contest.
The California native went into round four three shots off the lead but a closing 66 handed him the title and the season long honours as he went one better than countryman Patrick Reed, who finished second in the Race to Dubai in 2018.
"It's special, it's an honour, really, to be the first American to do that on the European Tour to put my name against many, many great Hall of Famers, it's special," he said. "I get touched up just talking about that.
"Two years ago, it wasn't my thought. It was, 'yeah, let's go play around the world' but we didn't know what the cards were going to be dealt.
"To have this chance and finally close it out, and not just closing it out with a top 10 or something, but to actually win the DP World Tour Championship, which concluded with the Race to Dubai, not a better way to finish - what a great way to finish.
"To close out the season-long race, the Race to Dubai, it means everything. Obviously I won some big events and that obviously helped catapult me up to the top.
"There are still a lot of scenarios that could have happened, especially today on this final round. Guys are not giving up, and I knew those guys that had a chance to possibly win and kick me out that have first spot, they weren't going to give up."
After starting his European Tour season at the Dubai Desert Classic, Morikawa won his first World Golf Championships title at the WGC-Workday Championship at The Concession, vaulting himself to second in Race to Dubai Rankings in Partnership with Rolex.
He would not drop out of the top three for the rest of the season, finishing in the top 20 at the Masters Tournament, top ten in his US PGA Championship defence and top five at the U.S. Open.
Having finished in the top ten on his Rolex Series debut in 2020 at Jumeirah Golf Estates, his second appearance in the Rolex Series resulted in a tie for 71st at the abrdn Scottish Open but greater things were to come seven days later.
A two-shot victory at Royal St George's Golf Club saw Morikawa crowned Champion Golfer of the Year and a second Major win on debut saw him move to the top of the Rankings, a position he would not relinquish for the rest of the year.
Among his other achievements in 2021, Morikawa was part of the victorious United States Ryder Cup team at Whistling Straits and finished in a tie for fourth at the Olympic Men's Golf Tournament after a seven man play-off for bronze.
Morikawa laid the foundation for his success with a stellar amateur career that saw him claim numerous titles, taking collegiate wins while studying at the University of California, Berkeley.
He reached Number One in the World Amateur Golf Ranking and played on victorious Walker and Palmer Cup teams before joining the paid ranks in 2019.
He made his European Tour debut in his second professional start at the U.S. Open Championship as he finished in a tie for fifth, and won in just his sixth professional event on the PGA Tour.
A second PGA Tour title followed in 2020 before he won his maiden Major at the US PGA Championship en route to finishing fifth on the Race to Dubai in his rookie season.