The Serbian was present at the O2 on Friday night to watch his Team Europe colleague bow out from competitive sport following a doubles defeat in the Laver Cup to Jack Sock and Frances Tiafoe.
Federer partnered up with Rafael Nadal - the other member of the 'big three' - for his last match but in keeping with the unique situation of the London event, Djokovic was one of the most vocal to provide support for two players who have usually been his biggest competitors.
An emotional goodbye to the pro game was afforded to Federer, who received a succession of ovations and had a retirement video package played on the big screen before singer Ellie Goulding produced a performance that left the Swiss star and Nadal in tears.
"We all knew it would be an emotional farewell for Roger but I think we were all taken away by the moment.
Djokovic, speaking after his singles' victory over Tiafoe on Saturday, said: "Well, I think we would all agree this was one of the most beautiful moments anyone has experienced live or on a tennis court worldwide.
"At the same time it is a mix of emotions. Sadness because one of the greatest athletes of all time is leaving the sport but on the other hand seeing him happy with the way it all played out, I was just very grateful and privileged to be alongside other Team World and Europe players to witness that.
"It was one of the most beautiful moments I have ever experienced in my life, for sure."
Federer had hinted in the hours after his 'last dance' that a potential farewell tour could be on the cards.
He had announced last week the doubles contest on night one of the Laver Cup, the Ryder Cup-style team competition he set up, would be his last on the ATP Tour but the door has been left open for more chances to see him on tennis courts around the world, just not in a professional capacity.
"I have no plans whatsoever like where, how, when. All I know is I would love to go and play places I have never played before or go say thank yous for years to come to all the people that have been so supportive of me," he said during a press conference that did not finish until after 2am on Saturday.
"Because the hard part about the Laver Cup was that tickets were already sold out. You know, the people who maybe would have also loved to be here couldn't make it. Maybe there is another way down the stretch we can party all together."
Defeat on a comeback was finally admitted publicly by Federer last week after a succession of operations during the last two and a half years on his right knee proved unsuccessful.
It meant the final singles contest of his career occurred at Wimbledon last year, where he lost in the quarter-finals to Hubert Hurkacz, but he insisted retirement, which he settled on last month, was no longer a scary concept.
He added: "I was able to remind myself always on the court again how wonderful this is.
"This is not the end, end, you know, life goes on. I'm healthy, I'm happy, everything's great and this is just a moment in time."
While Federer was emotional during his on-court interview, where he paid tribute to his wife Mirka, he was happy to bow out with a friend by his side in Nadal and they shared a long embrace after Sock's winner brought the two-hour-and-14-minute contest to its end.
"To be not alone on that court for an entire evening, it helped a lot," Federer admitted.
Nadal, who will forever hold a 26-14 upper-hand over Federer in singles, talked in depth about their "beautiful" friendship.
"For me, it has been a huge honour to be a part of this amazing moment of the history of our sport," the Spaniard insisted.
"When Roger leaves the tour, yeah, an important part of my life is leaving too. On court we have completely opposite styles and that's what probably makes our matches and our rivalry probably one of the biggest and most interesting.
"But in the family life, personal life, probably we approach life not in a very different way, no? So that's why we can trust each other. Having somebody like Roger that I feel confident to talk about any personal thing, it's something that is very beautiful after all the things that we shared together and all the important things that we fought for such a long time."