Filming on the judges' portion of American Idol kicks off on Tuesday, and ABC has secured its final judge spot in the nick of time. “I am very excited to be joining Katy, Luke and Ryan on American Idol,” Richie said in a statement. “As a singer, songwriter and producer, I feel I can bring a great deal of experience to the table. It’s going to be so much fun!” Luke Bryan also made his participation official, while Katy Perry tweeted: "SO excited, I feel like DANCING ON THE CEILING. Time to KICK THE DUST UP."