Part of it, is of course his unparalleled success on the tennis court, the other being his almost spotless public image. Federer's clean image makes him a particularly attractive draw for commercial sponsors.
Public relations Mark Borkowski says Federer is the "perfect package."
"When this man loses there's no tantrums. He is incredibly warm to people when they beat him. He's the sort of perfect package," Borkowski told the Sun.
"He is the ultimate pro. He's always delivered and at the height of his career he was winning everything in front of him.
"Brands want winners. Sponsors want to be associated with winners."
Reluctant to discuss figures, Federer is now in a league of his own when it comes to career earnings.
Forbes recently ranked him as raking in around $105 million last year alone in endorsements and prize money. According to Forbes, only basketball superstar LeBron James and footballer Cristiano Ronaldo are in the same earnings bracket.
According to the Sun, Federer is richer than Kim Kardashian, Elton John and even the Queen of England.
"I was excited to wear Uniqlo today. I must tell you, it's been a long time coming," said Federer about his latest sponsorship deal.
For the moment, Nike reportedly retains the rights to Federer's iconic 'RF' logo but the Swiss star anticipates ownership of that too in good time.
"The RF logo is with Nike, but it will come to me at some point," he added. "I hope rather sooner than later, that Nike can be nice and helpful in the process to bring it over to me.
"It's also something that was very important for me, for the fans really.
"They are my initials. They are mine. The good thing is it's not theirs forever."
Federer insists that he has not had a full divorce from Nike — hence the US company's shoes on the feet of the 20-time grand slam winner.
And it certainly isn't under Nike's best interests to completely part ways with the tennis star.
Regardless, Federer – a genius on the court and incredibly business savvy off it – seems like he's doing just fine.
Roger Federer's career by the numbers
Prize money: $157m
Won 20 Grand Slams including:
Wimbledon 2003, 2004, 2005, 2006, 2007, 2009, 2012, 2017
Australian Open 2004, 2006, 2007, 2010, 2017, 2018
French Open 2009
US Open 2004, 2005, 2006, 2007, 2008
Sponsorship $1 billion:
$412m – Uniqlo
$172m – Nike (just expired)
$115m – NetJets private jets
$68m – Mercedes-Benz
$53m – Barilla Pasta
$47m – Sunrise telecoms
$44m – Jura coffee
$41m – Moet & Chandon
$44m – Lindt
$32m – Wilson
$26m – Credit Suisse
$20m – Rolex Fee undisclosed – Gilette
Vehicles:
Six Mercedes including $270,000 AMG SLS Roadster and private jet
Bling:
Wife Mirka's emerald and diamond Rolex worth $680,000
His Rolex Sky Dweller is worth $53,000
Houses:
$27m glass mansion on shore of Lake Zurich
Holiday home in Swiss Alps
Penthouse in Le Reve tower, Dubai
