Djokovic wrapped it up at 1:37 a.m. local time on Monday, becoming the fifth man since the Open Era began in 1968 to win three straight Grand Slam finals.
The 24-year-old Djokovic tore off his shirt in celebration after the riveting final. He went to his support camp and repeatedly thumped the side of the arena in front of them in delight and relief.
Nadal leaned on the net, while Djokovic sat on his haunches before the trophy presentation. Eventually, an official brought them chairs and a bottle of water each.
"We made history tonight and unfortunately there couldn't be two winners," Djokovic said.
Djokovic maintained his mastery of Nadal, who has lost seven straight finals against the Serb since March last year.
The Spainiard became the first man in the Open Era to lose three straight major finals. He lost in four sets to Djokovic at last year's Wimbledon and U.S. Open.
Having reduced Roger Federer to tears when he won the title over five sets in 2009, Nadal maintained his composure during the on-court speeches -- and even managed a joke.
"Good morning, everybody," Nadal said, earning laughs and loud applause from the crowd. "Congratulations to Novak and his team. They deserve it. They are doing something fantastic, so congratulations."
After coming back from 5-3 down to win the fourth-set tiebreaker, Nadal was up a break at 4-2 in the fifth set against Djokovic, who seemed to be tiring.
But the No. 1-ranked Djokovic, who needed almost five hours to win his semifinal against Andy Murray, somehow responded. He broke for a 6-5 lead and saved a break point before finally claiming the win.
The previous longest major singles final was Mats Wilander's win over Ivan Lendl at the U.S. Open in 1988, which lasted 4 hours, 54 minutes.
The longest Australian Open final also involved Wilander in 1988, when the Swede beat Pat Cash. Sunday's match was also the longest in the tournament's history.
A tense, error-strewn opening set offered no indication of the high drama to follow. In hot, humid conditions, both players struggled for consistency.
After an exchange of breaks, Nadal took it after 80 minutes -- two minutes short of the entire women's final the previous day.
Nadal had only lost one match of his previous 134 in Grand Slams after winning the first set, but he found his serve coming under increasing pressure as the match wore on.
As if to demonstrate the pervading tension of the occasion, Djokovic double-faulted at break point down while serving for the second set at 5-3 before Nadal returned the favor by double-faulting in the next game to give the Serb the second set.
By the time Djokovic took a 3-1 lead in the third set, Nadal's shoulders were visibly slumping and he was talking to himself more often, unable to stop his opponent from peppering the baseline with his returns to take control of the points.
At 5-2, his uncle and coach Toni Nadal moved to the front row of the players' box to try to get some positive messages to his nephew.
It didn't work. Nadal lost his serve again -- at love.
But in the fourth set, Nadal dug in, drawing on his renowned fighting spirit, and the match really came alive when he recovered from 0-40 down in the eighth game with two spectacular winners, two unreturnable serves and an ace.
Then came a rain shower and a brief delay for the roof to close, robbing Nadal of his momentum.
He regained it the tiebreaker, though, reeling off four straight points from 5-3 down, taking the match into a decider when Djokovic's forehand dropped wide.
The tennis, almost unbelievably, seemed to improve in the fifth set as the match ticked past five hours.
At 4-4, Djokovic looped a backhand long after a 31-shot rally -- the longest of the match -- and then collapsed with his arms and legs spread wide.
He struggled to pick himself and his racket up, but he broke two games later when Nadal, finally showing signs of fatigue, netted a backhand.
Still, Nadal wasn't quite done. Djokovic had to save a break point with a cross-court backhand, crossing himself as he limped back to the baseline, before finally claiming victory with his 57th winner of the match.
Copyright 2012 by The Associated Press
