In the early hours of this morning, the American, who had previously won just once on the USPGA Tour (Phoenix Waste Management Open in 2015), claimed a four-shot victory.
Koepka turned in a supreme display, making three successive birdies from the 14th to stamp his authority.
His 16-under par total matched the total set when Rory McIlroy lifted the title in 2011.
Brian Harman could have secured sole possession of second spot, but bogeyed at the 18th to share second with Japan’s Hideki Matsuyama.
England’s Tommy Fleetwood had gone into the final day with a sniff of glory.
He started his final round one shot off the lead.
While he faded on the back nine, he carded a level par round of 72 to finish fourth.
The PGA Tour now turns its attentions to the Travelers Championship which gets underway on Thursday.
