Lionel Richie on Performing at Long-Time Friend King Charles III's Coronation (Exclusive)

The iconic singer opened up to ET at the 9th Annual Breakthrough Prize Ceremony.

Lionel Richie is going to be keeping the party going all night long when it comes time for King Charles III's forthcoming coronation.

The iconic singer and American Idol judge walked the carpet at the 9th Annual Breakthrough Prize Ceremony at the Academy Museum of Motion Pictures in Los Angeles on Saturday -- a star-studded gala honoring acclaimed science and mathematics luminaries -- and he spoke with ET's Denny Directo about being asked to perform at the historic Royal event.

"It's an honor," Richie said. "I mean, first of all, when you've been in the business a long time, and, of course, when you get an invitation like this, the answer is absolutely."

"We've been friends a long time, I've known him a long time, but to be asked is the whole thing," Richie added, referring to King Charles -- who Richie has worked alongside for many years as the founding Global Ambassador for the Prince's Trust, a charity Charles began when he was the Prince of Wales that seeks to help young people struggling to get their lives on track.

Richie's friend and Idol co-star, Katy Perry, was also announced as a performer at the grand coronation ceremony, set to be held on May 6, and Richie exclaimed, "Katy and I are going to represent, American Idol. When I tell you that, it's just correct."

"I mean, we do a lot for the Prince's Trust, so I'm happy to be there," Richie added.

As for preparing for the coronation concert itself, the "Hello" singer explained, "There's more secrecy than you've ever imagined in your life."

"I know what I'm going to do but when you ask, 'What is everyone else going to do?' Nothing. 'Who is everybody else?' 'Hmmm.' 'OK, well, what's the production going to be like?' [No response]," He said. "So we won't really know until we get there for the rehearsal to find out exactly how big."

"And, by the way, I'm going to use that word 'huge.' Not just big, [it's going to be] off the charts," Richie added.

Apart from Perry and Richie, additional performers set to sing at the star-studded coronation concert include Andrea Bocelli, British pop group Take That, Sir Bryn Terfel, Alexis Ffrench and Freya Ridings.

Although the actual anointment during the coronation ceremony is not broadcast publicly, plenty of special programming and live footage from the coronation ceremony will be available to watch live on May 6 starting at 5 a.m. ET. Cable viewers will be able to watch coverage on ABC News and  Good Morning America, including the concert featuring Katy and Richie. Others can watch the coronation online on these streaming platforms.