Herbert had a five-shot final-round lead slashed to one before regaining his composure to see off the challenge of Spanish great Sergio Garcia after a 22-minute rain delay in a dramatic climax to LIV Golf Virginia.
Too ill to complete a full practice round before the mega-money event, Herbert showcased all his character and grit in closing with a roller-coaster three-under-par 69 to win by four shots and collect a life-changing $US4 million ($A5.54 million) winner's cheque.
The Bendigo-born talent finished at 24 under for the 72 holes, with Garcia (70) edging out US superstar Bryson DeChambeau (66) by a shot to snare the runner-up spoils at Trump National Golf Club in Washington, DC.
Teammates Cameron Smith, Marc Leishman and Elvis Smylie showered Herbert with champagne on the 18th green after the 30-year-old's wire-to-wire triumph completed a full set of LIV Golf individual victories for the all-Australian Ripper GC outfit.
Leishman jagged his maiden title last year in Miami, before Smylie held off Jon Rahm down the stretch to score a thrilling one-shot victory at LIV Golf Riyadh in February.
Ripper skipper Smith is a three-time LIV winner but, ironically, the former British Open champion's most recent victory came before his three teammates' breakthroughs, three years ago in New Jersey.
With his seventh professional victory, Herbert has also now won on all four major worldwide circuits, having previously saluted on the US PGA Tour, Europe's DP World Tour and in Australasia.
"Probably that I can perform pretty damn well when things aren't perfect," Herbert said when asked what he'd learnt about himself.
"I was pretty sick all week and I woke up this morning probably feeling worse than I did the last few days.
"I had Sergio coming at me for 36 holes really hard and he pushed me the whole way, made me earn that one."
Despite the end margin, Herbert's success came anything but easily.
With four birdies in his first eight holes, he was cruising after rebuilding a five-shot advantage, having led by as many as eight strokes after a sizzling 64-63 opening to the tournament.
But after overcooking his nine iron on the par-3 ninth and needing three chip shots to find the green, Herbert racked up a dreaded double-bogey as Garcia drained a 30-foot birdie putt in a three-shot swing.
Herbert was suddenly clinging to a two-stroke lead heading to the back nine.
The buffer was just one when Garcia conjured a tap-in birdie at No.10.
But there was a further twist at the 11th, when Herbert holed a testing 12-foot downhill putt before Garcia missed his shorter birdie attempt to give the Australian some breathing space, two shots back in front.
Herbert was four clear again after picking up the sixth birdie of his round on 12 and the former Masters champion and all-time leading Ryder Cup point-scorer bogeyed 13, before slamming the door shut on Garcia with another birdie at 15.
"I didn't help myself," Herbert said.
"I missed a few putts here and there and made it a contest late, but after the rain delay, the way I played those eight shots, I'm so proud of that and can't wait to celebrate with everyone tonight."
Less than a week after Australasian PGA Tour boss Gavin Kirkman proclaimed Herbert was capable of winning a major, the Victorian will have another chance at the famed Shinnecock Hills from June 18-21.
"My first major ever was at Shinnecock (in 2018)," Herbert said.
"Nice to go back and see what I've learned since then. Can't wait to get there and try to play like I did this week."
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