The 20-time Grand Slam champion hung up his racquet after playing alongside Nadal for Team Europe against Jack Sock and Frances Tiafoe.
Federer and Nadal won 42 Slams between them between 2003 and 2022, and shared one of the most competitive rivalries in the history of tennis.
Federer says he was glad to have the Spaniard alongside him as he took to the court for the final time.
“It felt like a perfect ending, considering all the history, all the times I played against Rafa, that he could be next to me,” he told Andy Roddick during a live edition of Served at the Laver Cup.
“When I realised I wasn’t coming back, it was emotional but also peaceful.
“I could share that moment with my team, my rivals, my family, and the fans.
Curry enjoys tweener from Alcaraz in Laver Cup loss
Video credit: TNT Sports
“It was bigger than just me.”
Federer and Nadal were pictured crying as they sat next to each other after the doubles match.
The Swiss star admits that it was a relief to call time on his playing career after several injury issues.
“I felt relief in many ways, because the uncertainty was over,” he said.
“You live with this hope that maybe, just maybe, your body will cooperate again. But once I accepted it, the ending was beautiful.
“Sharing that with Rafa was not planned years in advance; it just happened that way. And I think that made it even more authentic.”
Federer was one of the founders of the Laver Cup, which started in 2017 and is being played this weekend in San Francisco.
He says it gives the greats of the game a chance to take centre stage and play a role alongside the stars of today.
Curry and Federer team up for legendary coin toss
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“In tennis, I feel we forget the legends of our sport,” he said.
“We don’t see them enough, we don’t include them enough. I’ve always been a little sad not to see all the heroes who paved the way for us more often.
“Prize money has gone up incredibly. Rod Laver maybe made a few million in his whole career.
“Carlos [Alcaraz] has already made $15m (£11.1m) just this year.
“I was always educated about the history of the game, and I thought: let’s bring the legends back, get them together for a weekend, give them a role.”
Despite the emphasis on the greats of the past, Federer demands that the active players take the event as seriously as any other. Â
“I never wanted it to be clowning around and giggling,” he added.
“There are exhibitions for that. At the Laver Cup, if fans buy a hefty ticket to see the best players in the world, they deserve real tennis. Smiles and fun, yes, but once the ball is in play, it must be with purpose, and to honour Rod Laver and the generations before.
“Being part of the inaugural Laver Cup was important for me, because I could help set that tone.”
How to watch the 2025 Laver Cup
The 2025 Laver Cup in San Francisco runs place from September 19-21, live on TNT Sports and discovery+.
Coverage of Sunday’s final round of matches gets under way at 20:00 UK time on TNT Sports 4.Â