The 27-year-old Koepka grabbed control with three straight birdies on the back nine at Erin Hills. He matched Rory McIlroy's U.S. Open record by finishing at 16 under.
Koepka takes home $2.16 million, the largest single-day earnings in golf. He also extends the streak of first-time major winners to seven.
Koepka became the third straight American to win the title. It's the first time that has happened since 1998-2000.
