King Charles and Queen Camilla Make Surprise Appearance on 'American Idol' with Lionel Richie, Katy Perry

The newly crowned King Charles and Queen Camilla have made their American Idol debut!

The royals, fresh from Saturday's coronation, joined Idol judges Lionel Richie and Katy Perry on the show for a surprise appearance on Sunday.

"Surprise! Their Majesties King Charles III and Queen Camilla join @lionelrichie and @katyperry from Windsor Castle! 👑," read the caption on a clip posted to the show's official Instagram page.

In the clip from Windsor Castle on Sunday, Richie, 73, and Perry, 38, began telling viewers about the "incredible" historical event they witnessed and said they thought of how they could bring "something different to the show" as Perry suddenly backed out of the way.

"Excuse me, Katy. I have a surprise," Richie said. Charles, 74, and Camilla, 75, then sauntered into frame, with Perry giving an "Oh goodness" before bowing to their royal guests.

His Majesty then uttered an "All Night Long" song reference then casually grilled Richie about how long they were going to be filming.

"I just wanted to check, how long you will be using this room for?" King Charles said with a sweet smirk and laugh for the bit, telling Richie, "Thank you so much. You're brilliant as always," and then acknowledged Perry as well, as Camilla smiled throughout the video.

They spoke of the "party next door," meaning the coronation concert, and Charles joked, "Oh, you've heard of it?"

He added, "I better take you to the party, but you're busy with these other things."

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"As soon as we finish ... we're coming to the party," Richie and Perry said in unison.

"Bless you," King Charles told Richie as they signed off, before Richie and Perry said together as the latter gave another quick bow, "Thank you so much!"

As for the duo's connection to the royals, the "Firework" singer has served as an ambassador of The British Asian Trust, a charity co-founded by Charles (when he was Prince) to tackle poverty and transform lives in South Asia, since 2020.

Meanwhile, the "Hello" hitmaker was appointed the First Global Ambassador and First Chairman of the Global Ambassador Group for The Prince's Trust in 2019.

Richie and Perry were the top headliners from Sunday's coronation concert and also attended the ceremony. Amid their absence, Ed Sheeran and Alanis Morissette stepped in as judges on Idol — and also performed.

Last month, Richie chatted with PEOPLE at the Breakthrough Awards in Los Angeles about what the honor and royal invite meant to him.

"I mean, you don't get in the business and say, 'You know what? I'll be at the King's coronation.' You know, that just never comes up," Richie said. "[It's] A, a surprise. B, what an honor. And C, the fact of all the names that are out there that he could have had for this, he called my name."

For the historical show, Richie played his Commodores hit "Easy (Like Sunday Morning)," then livened things up with his dance party hit "All Night Long," while Perry sang "Roar" and dedicated her performance of "Firework" to King Charles.

The event was attended by 20,000 members of the public from across the U.K. and members of the royal family. The concert was hosted by Downton Abbey and Paddington actor Hugh Bonneville.