The 29-year-old American needed to par the last hole to become the first LIV player to break 60, but finished with a birdie two to claim his first title on the new tour.
DeChambeau later tweeted: “It’s been a long time coming. This is one of the best rounds of golf I have ever played in my life. I can’t thank my team enough and sticking with me through the process.
“Today may have been history, but this is just the beginning. Let’s keep it going.”
DeChambeau carded 13 birdies and a single bogey to finish on 23 under par after 54 holes, six shots clear of Mito Pereira in second place.
It was his first victory since the death of his father Jon at the age of 63 in November last year.
Speaking at the greenside, DeChambeau said in a video tweeted by LIV Golf: “He was with me out there all day today, no doubt.
“It has been a really difficult couple of years, but doing it this way and finishing out with a 58… it’s just amazing what I was able to do. I’m super excited.”