The Swede birdied four of the last six holes in the Genesis Invitational at Torrey Pines on Sunday to complete a final-round 66 and finish 12 under par, one shot ahead of American Maverick McNealy.
McNealy had set the clubhouse target following a closing 64 but ultimately paid the price for covering the last five holes in one over par.
The 29-year-old had to hole from 38 feet to save par on the first, but birdied the next five holes in a row and picked up another shot on the ninth to reach the turn in 30.
Further birdies on the 10th, 11th and 13th briefly gave McNealy a three-stroke lead before he dropped his only shot of the day on the 14th after failing to get up and down from a greenside bunker.
Aberg, who had covered the front nine in 34, needed a strong finish to force himself into contention and duly birdied the 13th, 14th and 15th before two-putting from 70 feet for birdie on the par-five 18th.
The 25-year-old who turned pro in June 2023 after an outstanding amateur career, won the RSM Classic that year, then finished second three times in 2024, including at the Masters.
"It was awesome," Aberg, who goes to No.4 in the world, told CBS.
"It was a great fight.
"Obviously the golf course is tough but felt like I was in control of the ball flight all day and really proud of the way that I finished, it was really cool.
"The putt on 12 was big because I think at that point the lead was at 12 and it was a putt to stay at eight. I made it, which was nice, then a couple of a birdies and it was so much fun coming down the last few holes trying to win a tournament.
"It really is a special feeling."
McNealy, who had started the day five shots off the lead held by Patrick Rodgers, said: "It's more than I could have asked for to start the day.
"I had a few poor shots and an unlucky break or two at the end but definitely had a few things go my way early in this round and it was just a ton of fun to be up there, to have a chance. Ludvig played awesome."
World No.1 Scottie Scheffler, who shot a 76 on Saturday to fall into a tie for eighth, was 10 shots better on Sunday and finished at nine under, tied for third with third-round leader Rodgers (71).
England's Tommy Fleetwood (68) was part of a four-way tie for fifth at eight under.
Adam Scott (70) finished as the best Australian in a tie for 37th at one over, while compatriots Min Woo Lee (70) and Jason Day (72) were four and six over, respectively.
With AAP.
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