At Rod Laver Arena in Melbourne, the great man weaved his magic once again, clinching victory in the competition for the sixth time in his distinguished career.
In addition to the Norman Brookes Challenge Cup, Federer will take home £2.32 million in prize money, whereas Cilic will earn £1.16 million for his efforts, per the Daily Telegraph.
After a poor start, Cilic battled his way back into contention in the match, levelling things up on two occasions. But Federer was exceptional on the big points, unshakeable on serve and eventually just too good for his rival.
This is the moment Federer clinched his sixth Australian Open title after three hours and three minutes of play:
Here is a look back at some of the highlights from Sunday's showdown, as Federer further cemented his status as a sporting great.
Federer Makes it 20
Despite this being his 20th Grand Slam title, Federer was emotional during the official presentations after the match:
"I'm so happy," he said afterwards, per Jacob Steinberg of the Guardian. "Winning is an absolute dream come true. The fairytale continues for us, for me. After the great year I had last year, it's incredible. I'd like to thank Marin, another great tournament."
This statistic from Jon Wertheim of Sports Illustrated summed up just how long Federer has been at tennis' summit:
Meanwhile, journalist Lucas Navarrete suggested Federer should be considered as one of the greatest competitors in sporting history:
The final set was straightforward for Federer, but Cilic made the veteran work hard for his triumph.
Initially, it appeared as though this final may be over quickly, as Federer won the first four games in the space of 12 minutes. As the competition's official account noted at the end of the opening set, the Swiss' record after going ahead in Grand Slam finals is impressive:
Cilic performed well for the next three sets, as he shook off the nervousness that was clearly blighting him in the early stages.
He was crunching numerous forehands from the baseline and was a worthy winner of the second set. And while Federer did take the third, there was no let-up from the Croatian.
After Federer moved back in front, Stuart Fraser of The Times reminded us how good the Swiss is in this position:
It made Cilic's recovery in the fourth, especially after falling a break down, all the more impressive. And at the end of that set, it appeared as though the sixth seed was the stronger player, with Federer looking a little jaded in the longer exchanges.
Yet, as he has done so frequently throughout his incredible career, the second seed was able to find something special when it mattered most.
He broke early in the fifth, and while Cilic, who moved up to No. 3 in the world rankings after his final appearance, continued to scrap, there was a steeliness complementing Federer's style in the decider.
Another break of serve to move 5-1 in front effectively ended Cilic's chances, and Federer wrapped up the match with minimal fuss.
It will be intriguing to see how Federer approaches the rest of the year, having sampled success in Melbourne for a sixth time; in 2017, he skipped the French Open before winning Wimbledon. It's clear that, even at 36, the Swiss still has a lot to offer.