In an engrossing showdown between the two top seeds, the Dane edged a tight first set, before the world No. 1 fought back.
That set up a tense final set that contained numerous breaks of serve. But eventually, the second seed was able to retain her composure and show her best on the clutch points, breaking Halep to win the decider.
As well as the Daphne Akhurst Memorial Cup, victory here also sees Wozniacki usurp Halep as the world No. 1 in the WTA Rankings.
Here's the moment the second seed secured the biggest victory of her career, per Eurosport UK:
It was Wozniacki who settled quickest. The Dane put together a strong opening service game and was on the front foot in the second, too, as Halep struggled to get into a groove.
At 3-0 down, the Romanian did find a foothold. Halep improved on serve, and after getting her first game on the board, she appeared a lot more relaxed.
The competition's official Twitter account commented on a crucial moment:
Wozniacki continued to get games in the bank on her serve, moving to within one game of the opener at 5-2 in front. It was at this point where Halep produced her best tennis of the set, holding to cut the deficit and then unleashing some massive forehands to break.
The top seed levelled at 5-5 and momentum was with her, as she was able to salvage a tiebreak from the set.
In it, Wozniacki again started the brighter, as she got the better of some gruelling rallies to move 4-1 ahead. From there, the second seed was in control and drove her dominance in the breaker home with a 7-2 triumph.
Tennis journalist Simon Cambers commented on a fascinating first set, during which both players showcased some sparkling stuff:
A Halep hold was followed by a Wozniacki hold at the start of the second stanza before a crucial third game.
It included four break points for the Dane and numerous fantastic rallies, but it culminated with Halep holding and keeping her nose ahead in the second set. Even so, Wozniacki was proving tough to shake off, as a tense second set stayed on serve.
There was a nervy moment for spectators midway through the set when Halep appeared in some distress.
As noted by Nick McCarvel, the conditions were challenging for the two players:
Despite this, Halep was still a force on court, and in the eighth game, she pounced on some soft serves from her opponent to conjure two break points. She sealed the first of them with a delightful backhand down the line.
Serving for the set in the next game, Halep did eventually send this one into a decider, winning the second set 6-3.
Christopher Clarey of the New York Times reflected on a final on a knife edge after two absorbing sets:
At the start of the decider, Halep appeared to be struggling with her movement. Wozniacki, to her credit, was able to capitalise and dictate with her backhand; the first break of the deciding set went to the Dane, who moved 2-0 ahead.
It was at this point the match became scrappy, with both players showing signs of pressure being felt. Halep was able to break back, and the next two games went against serve. Eventually, Halep, who appeared to be getting a second wind, was able to hold and level at 3-3.
As we can see, the top seed was conjuring some wonderful shots:
In the same game, Halep was able to break her opponent for a third time, moving ahead in the final set. But in the next, it was Wozniacki's turn to dig deep, as she broke again to make it 4-4.
WTA star Heather Watson commented on a final that was shaping into a classic:
Wozniacki was able to finally win a game on her serve to move 5-4 ahead and, tantalisingly, one game away from the title.
To set up match point, the Dane played a remarkable point, coming out on top in an incredible rally. And when Halep netted in the next rally, Wozniacki sunk to her knees in exhaustion, relief and delight.