Chacarra is in just his second season on the DP World Tour. He earned around $15 million to $20 million during three years as a LIV player.
The finish added another title to McIlroy's record at the end of a long, hard season that came down to a head-to-head with Chacarra.
That contest dominated the tournament and ran right to the wire.
Both players knew victory would win them the order of merit. They went toe to toe, and the overall lead chopped and changed down an absorbing back nine as neither man backed down.
Chacarra responded with two more birdies and pushed McIlroy all the way before finishing in a tie for third.
The 26-year-old world number 39 ended second in the overall standings and earned a PGA Tour card for next season.
McIlroy's targets have changed. He is not chasing the world number one spot or winning any available trophy.
He has voiced a desire to focus on the majors, play more in Europe and around the globe, and keep stacking order of merit titles.
After this latest addition to his record, one of those targets is to nail down his claim as Europe's greatest golfer.
Rahm and Hatton, two high-profile LIV players, are suspended from the PGA Tour for a year following their involvement with the breakaway tour.
Both will have a full season on the European circuit, a schedule that will give them a big advantage over McIlroy.