The Dane, who will become the new world number one, burst into tears as she secured the championship 7-6 (7/2), 3-6, 6-4 against the battling Romanian top seed on her first match point of a gruelling, epic encounter.
“I’ve dreamt of this moment for so many years,” said second seeded Wozniacki after becoming the first player from Denmark to win a Grand Slam.
“My voice is shaking. I never cry, but this is a very emotional moment.
“I want to congratulate Simona, I know it’s a tough day,” she added after receiving the trophy from Billie Jean King.
“I’m sorry that I had to win today but I’m sure we’ll have many matches in the future and it was an incredible match and an incredible fight and again, I’m sorry.”
Wozniacki, 27, had to overcome bouts of nerves throughout the long match. She wobbled when serving for the first set at 5-3 and had to come through a tiebreak.
“I want to thank my fiance,” she said, looking up to American basketball player David Lee in her box. “I was a nervous wreck this morning, I wanted to win so bad, but you calmed me down.”
Both players needed medical attention on court before the Dane prevailed in 2hr 49min on Rod Laver Arena.
For Wozniacki, victory meant shedding at last the unwanted moniker of best player never to win a major, having reached the US Open final in 2009 and 2014, and first becoming number one in 2010.
For Halep, who surrendered her number one status to Wozniacki in defeat, the wait goes on.
“It’s not easy to talk now but first of all I want to congratulate Caroline,” said Halep, who was also appearing in her third Grand Slam final and first in Australia.
“She played amazing. It’s been a great tournament for me. Of course I’m sad I couldn’t win today but Caroline was better than me.
“But I will fight and hopefully I will face another challenge like I did today. I’m sad that I couldn’t make it the third time, but maybe the fourth time will be with luck.”
– Worrying scenes –
Wozniacki started the stronger, breaking Halep’s opening service game with the early evening temperature still above 30 Celsius (86 Farenheit) before racing into a 3-0 lead.
She had not won a set in either of her previous two Grand Slam final appearances and tightened visibly serving for this one, and the set headed for a tiebreak.
The Dane went 4-1 up before a second mini-break and two solid serves gave her the tiebreak 7-2.
Wozniacki was growing in confidence and Halep needed to save four break points at 1-1 in the second set in a brutal game that lasted 11 minutes.
Soon after Halep signalled to her coach Darren Cahill that she wasn’t feeling well and there were worrying scenes as she had her blood pressure taken and an ice towel applied in the next changeover.
She re-emerged with her energy drained and needed the luckiest of net cords to hold for 4-3.
Cramping, she decided to stand and deliver in the next game, keeping the points short.
Incredibly the tactic paid off as she broke Wozniacki with a ripping drive up the line to level the match.
The tournament’s extreme heat policy was invoked meaning the players took a 10-minute break before the start of the third set.
When they resumed neither of them could hold their serve until Wozniacki, after having a timeout to have her left knee strapped, held for 5-4 to force Halep to serve to stay in the match.
She couldn’t manage it and a backhand into the net brought an end to her brave challenge.