The 32-year-old had come close last year, losing in a playoff at the Irish Open after Russell Knox made several ludicrous putts to deny him the title. His start to 2019 was steady, making four of five cuts and finishing in a tie for sixth at the Saudi International, before he truly made his mark in Perth.
"I've been close a couple of times and it's certainly nice to get one over the line today," said Fox.
"Adrian didn't quite play his best this afternoon but I'm quite happy to take advantage of that.
"I played great, and felt probably the most under control I have in all the matches so far, so it was nice to finish in style."
It was a clinical display when it mattered, especially considering the inherent randomness of strokeplay – especially six-hole strokeplay.
After progressing through three close encounters, he made the most of Otaegui's struggles in the final, making par on the first hole when the Spaniard bogeyed, before his opponent found trouble on the second as Fox stayed steady to go 2-up.
Fox then smashed his drive on the third hole right down the middle, before sinking a 15-foot putt to make it three from three, and merely needed to halve the fourth hole to take a victory with two holes to spare.
That he did, tapping in for a par that sealed his first European Tour title, and the first by a Kiwi male on the European Tour since Danny Lee won the Johnnie Walker Classic in 2009.
Fox joins the likes of Michael Campbell, Bob Charles, Frank Nobilo, Greg Turner, Mark Brown and Lee in claiming titles on the European Tour, while Lydia Ko has won five times on the Ladies' European Tour.
The win also projects him to rise more than 20 places to 64th in the world rankings, within touching distance of the top 50 that ensures automatic entry into events such as the Players Championship, the Masters, and the Open Championship.