Sinner, who has a doping case hanging over his head, said he was fired up coming into the match despite his calm exterior.
“In your mind there is only one match left. You want to empty your tank a little bit. That was what I was trying to do,” he said.
“It is definitely a different feeling for sure,” he added of winning a second Melbourne crown.
“I know how much work I put into this one and having this one twice it’s amazing.”
The win proved more misery for Germany’s Zverev, who remains one of the world’s best players never to taste Grand Slam glory, falling short once again in his third big final.
“It sucks standing here next to this thing [the trophy] and not being able to touch it, I’ll be honest,” said the 27-year-old.
“But congratulations to Jannik. You more than deserve it. You’re the best player in the world by far. I was hoping that I could be more competitive today, but you’re just too good. It’s as simple as that.”
Ice-cool Sinner proved to be a tower of mental strength again in Australia, with his defence coming against the backdrop of an ongoing doping case after he twice tested positive for traces of the steroid clostebol last year.
The World Anti-Doping Agency appealed against his exoneration and is seeking a ban of up to two years. He denies knowingly doping.
A hearing is scheduled at the Court of Arbitration for Sport (CAS) for April.
He cast all the worries aside to notch a 19th career title and extend his incredible winning streak to 21 matches, sharing words of consolation with Zverev.
“A tough day for you. You’re an amazing player. Keep believing in yourself because I think we, all the players and the coaches, whoever is involved in the sport, know how strong you are, not only as a player, but also as a person.
“So keep it up. Keep working hard because we all believe that you can lift one of these very, very soon.”
Last year Sinner needed five sets to tame Daniil Medvedev and win his first Grand Slam, but it never looked like going the distance this time.
The US Open champion opened with a statement ace and won his first two service games to love, with Zverev struggling to get himself into the contest.
The German began to find his radar, taking four points off one Sinner serve in a game that went to deuce twice as the rallies built.
But the dam burst in the eighth game.
Zverev saved three break points but had no answer to a fourth when he was beaten by a blazing passing shot to slump 5-3 behind.
Sinner took the set in 46 minutes and kept the pressure on in the second.
The Italian has a phenomenal ability to turn recovery shots into momentum-changing ones and he raced 15-40 clear on the Zverev serve at 1-1.
Once more, the second seed dug deep to cling on.
From then on they couldn’t be separated and it went to a tiebreak where Sinner got a lucky net cord that dribbled over to break for 5-4 and he streaked to a two-set lead.
Zverev smashed his racquet in frustration at the changeover and it didn’t get any better in the third set, worn down by the relentless Italian.
Sinner broke for 4-2 when Zverev sent a forehand long and there was no way back for the increasingly disillusioned German.
