Mickelson, playing in the final group for the first time since joining the Saudi-funded circuit last year, hit two tee shots in the water and made a quintuple-bogey 8 on the par-3 seventh hole at Trump National, effectively ending his hopes.
Smith, who had two early bogeys that dropped his lead to three shots over Mickelson at the time, closed with five birdies and a clean card for a 3-under 68 and seven-shot victory.
Smith won for the second time in three LIV Golf events and took over the season points race in his attempt to claim the $18 million bonus at the end of the season.
He finished at 12-under 201.
“That was the goal since the start of the year, to be up with a shot at it,” Smith said of the season points race. “Got a couple of weeks left.”
LIV Golf is now off for the next five weeks until returning outside Chicago.
Mickelson ended an attention-filled week with a 75. He tied for ninth, his first top 10 of the year. The day before the tournament began, an excerpt from gambler Billy Walters’ book was released that claimed Mickelson placed over $1 billion in bets over the last 30 years and asked Walters to bet $400,000 on the U.S. team to win the 2012 Ryder Cup that Mickelson played in.
Mickelson said he never placed a bet on the Ryder Cup.
Smith earned $4 million for the win, raising his total to just over $13.6 million for the year. He said he would put the clubs away for the first few weeks of his break.
“My clubs deserve a rest,” Smith said.
His Ripper team won the team competition by 11 shots.