He gathered momentum ahead of next month's US Open.
Dustin Johnson will go into the US Open later this month as the Fed Ex Cup Champion.
The American won the Tour Championship by 3 shots from Justin Thomas and Xander Schauffele.
Rory McIlroy finished in a tie for 8th.
Johnson - who collects a purse of 15 million dollars for his victory - says finishing the season as the PGA Tour's top player has always been a dream:
Super pumped to finally win the FedEx Cup. Thank you to my team and supporters! My brother Austin, all the fans, @TaylorMadeGolf, @DJGolfSchool, @netjets, @Hublot, @adidasGolf, @RBC, @DrinkBODYARMOR.— Dustin Johnson (@DJohnsonPGA) September 7, 2020
A little rest and then prep time for Winged Foot. pic.twitter.com/UHDcloP1xV