The 23-year-old came through a tense battle between the world's top two players 6-3, 7-6 (7/4), 6-3 on Rod Laver Arena, raising his arms in the air and looking to the sky in celebration.
The victory earned the Italian world number one his third Grand Slam crown.
The former world number one responded on Saturday, posting a photo of an MRI taken of his left hamstring on the social media platform X with the caption: "Thought I'd leave this here for all the sports injury 'experts' out there."
It is Keys's first major title, having reached a second Grand Slam final eight years after her first in New York. She lost on that occasion to Sloane Stephens
Sinner's coach Darren Cahill said it was no surprise for him to see his young charge back in the final, but they were wary of the threat posed by Zverev's overarching desire to finally win a Slam.
The American battled injury and self-doubts last year and curtailed her season early, in October, to get married.
Swiatek said she made far too many mistakes against Keys on Rod Laver Arena and hoped to draw lessons from it.
The 19th seed powered through a thrilling semi-final on a final-set tiebreak against the world number two 5-7, 6-1, 7-6 (10/8) after Sabalenka had earlier swept aside Paula Badosa in straight sets.
The Italian top seed faces Ben Shelton on Friday, just two matches away from a first successful Grand Slam title defence after winning his maiden major crown in Melbourne last year.
Top seed Novak Djokovic was drawn Thursday against a qualifier or lucky loser to begin his bid for an 11th Australian Open crown, and could meet fellow Grand Slam champion Andy Murray in the third round.
Italian Jannik Sinner's climb towards the top of men's tennis could hardly be described as sluggish unless of course a direct comparison is made with Spanish phenomenon Carlos Alcaraz.
The 36-year-old from Serbia defeated Stefanos Tsitsipas in last year's final for a record-extending 10th Melbourne crown then added the French and US Open titles to his collection in 2023.
Coco Gauff held her nerve to beat Elina Svitolina in a gruelling three-set final on Sunday to retain her Auckland Classic title in an ideal warm-up for the Australian Open.
Elena Rybakina will head to the Australian Open full of confidence after demolishing world number two Aryna Sabalenka in the Brisbane International final on Sunday.
The 22-times Grand Slam champion had arthroscopic surgery last June after injuring his left hip flexor during his second round defeat by Mackenzie McDonald at the Australian Open in early 2023.
The world number one holds no grudges heading into the mixed team event nearly two years after being refused entry to the country over his stance on Covid-19 vaccinations
The 37-year-old has not played since a second-round loss at the Australian Open this year, undergoing two rounds of hip surgery on the long road back.
The rise means the prize pot at the Melbourne Park Grand Slam has more than doubled over the last decade but the cash is now far more evenly distributed.
Showstopper Nick Kyrgios and former US Open champion Emma Raducanu were notable absentees Thursday from the 2024 Australian Open entry list, but Rafael Nadal and Naomi Osaka are set for their Grand Slam comebacks.
