The 26-year-old Swede made two eagles and six birdies against a lone bogey to stand on 12-under 132 after 36 holes at TPC Sawgrass in Ponte Vedra Beach, Florida.
Aberg answered his first bogey of the week at the par-four 15th with birdies at the par-five 16th and par-four 18th for the lead.
"It was good, fought all the way to the end," Aberg said. "It was nice to birdie 16 and 18. Overall very pleased."
Xander Schauffele, the 2024 PGA Championship and British Open winner, was second on 134 after a 65 on Friday with fellow American Cameron Young third on 135, plus Canada's Corey Conners and American Justin Thomas fourth on 136.
"For the most part I felt like I was in control and felt like I was attacking the golf course versus playing defensive," said Schauffele, who found every fairway. "It's always easy to be aggressive from the fairway here."
Aberg, the 2024 Masters runner-up, seeks his third PGA Tour title after the 2023 RSM Classic and last year's Genesis Invitational.
Aberg, third last week at Bay Hill, matched his lowest career 36-hole score to par, helped by two eagles on the front nine.
He birdied the first hole from just inside four feet, eagled the par-five second from just inside 15 feet, sank a 10-foot birdie putt at the par-three third and curled in a 23-foot chip to birdie the fourth.
"I got off to a really nice start, made some nice putts and even chipped in on four," Aberg said. "It was a good day. It was nice to see those things show up.
"Even though I felt like middle-round-ish, I struggled a little bit off the tee, I thought I came back into it and hit some really nice tee balls coming down the last few holes."
Aberg, standing in a bunker, chipped in from 34 feet for eagle at the par-five ninth for only the third front-nine 29.
"I knew it was an aggressive play getting a 3-wood up there," he said. "I felt like I would have a chip from somewhere up there. It's always a bonus when those go in."
Aberg birdied the par-five 11th from just outside four feet but stumbled at 15, missing the green on his approach and sinking a testy bogey putt from just inside eight feet.
He responded by dropping his approach inches from the hole at the par-five 16th for a tap-in birdie and finished with a birdie putt from just inside eight feet.
Top-ranked Scottie Scheffler fired a 73 to stand on 145, one stroke inside the cut line.
World number two Rory McIlroy, the defending champion, fired a 71 to also stand on 145 and was not hampered by a back injury that forced him out last week at Bay Hill.
"I didn't really feel anything, I woke up this morning felt fine," McIlroy said. "It feels pretty much there. Not all the way there, but I feel like it's just progressively getting better each and every day."