Players are required to wear clothing that is almost entirely white from the time they enter the arena at Wimbledon to the time they leave the court, and Kyrgios had been pulled up by a reporter for disregarding protocol after his fourth round win over Brandon Nakashima.
Told he'd receive a fine for his fashion faux pas, the Australian said at the time: "I do what I want."
That attitude extended all the way to the decider and his meeting with royalty. The Duchess of Cambridge is the royal patron of the All England Lawn Tennis and Croquet Club — so would be well aware of the rules — but Kyrgios still dared to don his red cap when she handed him his trophy on Centre Court.
British tennis writer Mike Dickson called Kyrgios' rogue move a "final act of defiance", while plenty of others on social media also weighed in.
Editor Kevin Palmer tweeted: "A rebel to the end. Nick Kyrgios has been told not to wear his red hat on Centre Court. He simply doesn't care!!"
Journalist Uche Amako wrote: "Real zero f**** vibe from Nick Kyrgios as he receives his runners up plate with his red Nike Jordan cap on."
Reporter Rayane Tamer said: "Nick Kyrgios … in a … red hat for the grand final formalities. Sending a message."
"Ok Nick, you lost & you were a good sport in the handshake with Novak," said one fan. "But lose the effing red hat. Show some respect to the tournament & traditions while you're still centre stage."
After being put in the spotlight for his choice of headwear — and slipping on red shoes too — against Nakashima, Kyrgios stuck to tradition in his quarter-final win over Cristian Garin. However, he was back at his colourful best for the final match at Wimbledon in 2022.
Following his five-set win over Nakashima last week, Kyrgios shut down a journalist who tried to press him on the issue during a media conference.
Reporter: It's interesting your comments earlier about the controversy that just seems to materialise around you. We all know the Wimbledon dress code rules are very strict. Competitors must be dressed in suitable tennis attire that's almost entirely white - and this applies from the moment in which the player enters the court surrounds. Why then would you walk on to centre court with bright red trainers on and do an interview in a red cap?
Kyrgios: Because I do what I want.
Reporter: So you're above the rules?
Kyrgios: No. I'm not above the rules.
Reporter: So what is it? They don't apply to you?
Kyrgios: I just like wearing my Jordans.
Reporter: But there are rules specifically against that. I don't want to spoil the surprise but the referee's going to be speaking to you about it.
Kyrgios: That's OK. I'll wear some triple whites tomorrow.
Reporter: But that's fine then. No one else, in both draws, wears …
Kyrgios: But no one else - even after Wimbledon - no one else really walks with Jordans on the court.
(Moderator tries to interject)
Reporter: Sorry, but Nick has just moaned about the controversy that surrounds him.
Kyrgios: I haven't moaned. I love it.
Reporter: So you just laugh it off then?
Kyrgios: Yeah, it's just more attention for me. What's that saying? Any publicity is good publicity, right?
Reporter: If you say so.
Kyrgios: Keep doing you then champion.
