On the third playoff hole, he holed his putt to win the tournament, his first on the tour.
They both made it to the first two playoff holes and both made it to the second playoff hole.
After Uihlein's third shot from the sand went into the water, Koepka hit a textbook shot and made a putt to win.

After revealing that he had feared for his career while battling injury, the four-time major winner was emotional.
The last couple of years have not been enjoyable. It's been a long journey. I was not sure if my career was over for a second. It's great to be able to win.
The Royal Greens Golf and Country Club in King Abdullah Economic City had a leader after the first round but was overtaken by Uihlein on the second day.
They were in a four-way tie for the lead at the final hole, but both of them made pars to force a playoff.
Uihlein had a 1-under 69 and finished at 12 under.
The result saw Uihlein take third place with a prize of $4 million, and second place with a prize of $8 million. The LIV individual champion title has been won byDustin Johnson.
Individual and team play took place at the seventh and final LIV golf invitational. Four-man teams will be in Miami in two weeks for the finale of the inaugural season.
This was the first tournament held in Saudi Arabia after other tournaments in London, Portland, Oregon, Bedminster, New Jersey, Boston and Chicago.
The prize money at LIV Golf is $25 million. The players who have been drawn to the large prizes have been banned from playing.