The 35-year-old, who is the son of All Blacks rugby legend Grant, claimed a second DP World Tour victory this season and third in total after holding off a thrilling last-round charge from world No 2 Rory McIlroy on the Old Course.
Fox, who had started the day four shots behind overnight leader Richard Mansell, hit the front after going out in three-under before giving himself some breathing space following birdies at the tenth and 12th.
Following a bogey at the 13th, he then rolled in a 56-foot birdie putt at the 15th before making a good bogey at the 17th with a two-putt from long distance after duffing a pitch with his third shot.
Having been three shots clear with three play, the cushion was down to just one standing on the 18th tee, where Fox watched Swede Alex Noren, one of his playing partners and hurting after missing a short birdie putt at the 17th, see his tee shot come back into play after heading out of bounds, before opting to go with a utility club.
That effectively took any danger out play and it was job done for Fox, who is coached by Fife-based Jamie Gough, as he signed off with a rock-solid par on a glorious autumn afternoon on the east coast.
A closing 68 for a 15-under-par total gave the Auckland man a one-shot success over 2016 Scottish Open champion Noren after he made the most of his lucky last-hole break to finish with a birdie for a 69 and Englishman Callum Shinkwin, who birdied three of the last five holes for a 67.
McIlroy, who signed for a second successive 66, shared fourth spot with Frenchman Antoine Rozner (69) on 13-under, with a disappointing 76 leaving Mansell in a group on 11-under that included fellow Englishman and two-time winner Tyrell Hatton (67).
Grant Forrest (67) and Connor Syme (69) finished in a tie for tenth on ten-under, two ahead of Bob MacIntyre (68), but the day belonged to Fox as he became the first Kiwi to triumph at the home of golf.
“It means a lot,” admitted Fox of a win that was worth £763,000 before quickly paying tribute to Shane Warne, having partnered the Australian cricket legend in the pro am in the past and being left shocked following his sudden death in March.
“To be honest, the only person I can really think of at the moment is Warney. Means a lot to this event and great mates, and just a shame he's not here. I'm going to enjoy this one with the family.”
Fox landed his maiden tour triumph in the 2019 ISPS Handa World Super 6 in Perth, Australia, before adding the Ras al Khaimah Classic earlier this year, but this title triumph was on a different level.
He’d moved into contention on the back of a seven-under-par 65 at Kingsbarns on Saturday and it was classy stuff as he chalked up that third title after finishing second in the Soudal Open, Dutch Open and Horizon Irish Open since his success in the UAE in February.
“There was some luck out there,” added the first Kiwi winner in Scotland since Charles landed the John Player Classic on the Ayrshire coast in 1972. “Obviously I was pretty nervy the last three holes. I didn't hit very good shots 16, 17, 18. He [Warne] was definitely helping out, the putt on 15, the tee shot on 16.
“I was just trying not to make mistakes. I knew where I was and it's a hard golf course to do that. It's almost an easy golf course when you're chasing and unfortunately like you have some chances. Bad shots are really penal those last five holes. As bad as it sounds, I was just trying not to hit really bad shots and I think I got away with it for the most part.”
Having started the year sitting just outside the top 200 in the Official World Golf Ranking, Fox is set to climb as high as 25th in the updated standings and has almost certainly secured his debut in The Masters next April.
“I haven't had a chance to think about it yet but I'm sure I'll get many messages about that tonight. Unreal. Words can't describe anything at the moment, to be honest,” he admitted.
In the DP World Tour Rankings, he’s up to third behind McIlroy and US Open champion Matthew Fitzpatrick. “I wouldn't say it was a goal at the start of the year but it was certainly a goal after the mid part of the season,” he admitted of having a chance to finish the season as No 1. “It's been a tough couple of weeks (having to withdraw after the opening round of the BMW PGA Championship due to an injury then missing the cut in last week’s Cazoo Open de France) and it was nice to find some form again. Hopefully I can challenge Rory in the back end of the year.”
For McIlroy, it ended up being a case of close but no cigar for the second time this year at St Andrews. In July, he had to settle for third place behind Australian Cameron Smith in the 150th Open after seeing his putter turn cold on the final day.
The four-time major winner putted well on this occasion and did little wrong from tee to green again only to be denied by an Antipodean once more at this venue.
“I played well again,” said McIlroy. “I did everything I wanted to do until I didn’t make birdie on 14. That halted any momentum I had.” He then dropped a shot at the 17th after having to play out sideways from the Road Hole bunker.
“I just had visions of myself leaving it in there,” he said of that decision. “If it was ten years ago and I was in my exuberant youth, I would have tried it. But I know better these days.”