Jon Rahm has ended his first year in the LIV Golf League by closing with a four-under 66 to win the final individual event and the season points title with its $A26.8 million bonus.

Rahm missed a pair of short birdie putts on the back nine that kept Joaquin Niemann and Sergio Garcia in the mix. But then he holed a 12-foot birdie putt on the 17th hole that gave him a three-shot going to the last at Chicago's Bolingbrook Golf Course.

Rahm won for the second time in the Saudi-funded league, adding to his title in England last month.

Niemann, a two-time winner at the start of the season, was the only player who could have challenged Rahm for the season title. He opened with two early birdies but never could get ahead, closing within two shots after a birdie on the 15th and a big par save on the 16th.

Niemann shot 66, while Garcia shot 68. They tied for second.

The leading Australian was Lucas Herbert who shot 68 and tied for sixth, moving him into the top 24 that assures him a spot in the LIV Golf League next year.

Rahm, who finished at 11-under 199, won $US4 million ($5.96 million) from the tournament and $US18 million ($A26.8 million) for capturing the season race.

"I wanted to do a good show and get it over the line. I'm really happy," said Rahm, who said he was nervous on the practice range. "To go bogey-free on the weekend, it's quite spectacular. I'm very proud of the putt on the 17th, which made 18 a lot easier."

Of the other Australians, Matt Jones tied for 23rd at even par, Marc Leishman tied 34th at two over and Cameron Smith struggled to finish 52nd in the 54-player field at 10 over.

Rahm was the biggest name to join the Saudi-backed league last December and was in the top 10 at every LIV event he completed.

He had to withdraw from the Houston event with a toe infection, which also knocked him out of the US Open.