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.
The Italian world number one showed no signs of the illness that hampered him in his last match to emphatically fly past the eighth seed 6-3, 6-2, 6-1 on Rod Laver Arena.
The Polish second seed was phenomenal on a gusty day at Rod Laver Arena, powering past the eighth seeded-American 6-1, 6-2 in 1hrs 29mins.
The irrepressible 37-year-old put to bed any doubts about his ability to add to his 24 Grand Slam titles with a scintillating four-set takedown of Carlos Alcaraz in the Melbourne last eight on Tuesday.
Aryna Sabalenka kept a historic Australian Open hat-trick on track Tuesday as she battled past Russian 27th seed Anastasia Pavlyuchenkova 6-2, 2-6, 6-3 in the quarter-finals.
Coco Gauff said she was "disappointed but not completely crushed" after her scintillating start to the year came to an abrupt halt in the quarter-finals of the Australian Open on Tuesday.
Badosa reached a Slam semi-final for the first time in her career -- the first Spanish woman to do so since Garbine Muguruza at Melbourne in 2020.
Svitolina, the 28th seed, followed up her shock win over world number four Jasmine Paolini in the third round with a 6-4, 6-1 victory over the world number 75 on Rod Laver Arena.
Djokovic, speaking at a news conference in Melbourne where he is taking part in the Australian Open, said that he cannot "pretend that nothing is happening".
The 37-year-old Serb, who is gunning for a record 25th Grand Slam title and 11th Melbourne crown, beat 24th seed Jiri Lehecka 6-3, 6-4, 7-6 (7/4) on Rod Laver Arena.
Coco Gauff wrote "RIP TikTok USA" and drew a broken heart on a camera lens shortly after reaching the Australian Open quarter-finals on Sunday after the popular app used by 170 million Americans stopped working in the United States.
