“American Idol” runner-up Adam Lambert is set to join the cast of “Glee” when the show returns for a fifth season this fall.  

Showrunner and co-creator Ryan Murphy broke the news in a tweet last night. "I am thrilled to announce that the super talented Adam Lambert is joining the cast of Glee this fall," he announced.

According to the Hollywood Reporter, representatives for 20th Century Fox Television did not confirm if Lambert would be joining the popular musical dramedy as a series regular, a guest star or a recurring character.  

For years, there have been rumors that the singer would make an appearance on the show in some capacity. As Yahoo! TV notes, cast member Lea Michele (Rachel) lobbied to work with the singer in an interview from 2009. "I want to sing with Adam Lambert so badly!” she said. “I think he is so incredibly talented. He's a vocal freak. It's like working out: If you want to work out well, then you want to train with the best … that's how I feel about Adam Lambert. That's my metaphor."

Lambert himself expressed some initial misgivings about the series, but he eventually became a fan. “When Glee first came out, I was like, ‘I don't really like this show,’” he said. “But now I watch it... And you know what? I do think the show has an agenda, but I respect the agenda. I think it's a very brave agenda to try to push. I think that they're one of the few people that are doing it. So it's definitely one of a kind and very revolutionary in that way.”

Lambert will join the likes of Kate Hudson, Sarah Jessica Parker and Gwenyth Paltrow, all of whom have made high-profile guest appearances on “Glee.”

The news comes amid a sea of changes for the Fox series. As the Hollywood Reporter points out, original cast members Heather Morris (Brittany), Mark Salling (Puck), Amber Riley (Mercedes) and Harry Shum Jr. (Mike) will be relegated to sporadic guest appearances in the fifth season.  Newer talent Melissa Benoist (Marley), Jacob Artist (Jake), Becca Tobin (Kitty), Blake Jenner (Ryder) and Alex Newell (Unique) have been bumped up to series regulars.

Meanwhile, Jayma Mays (Emma Pillsbury) has signed on to a new CBS series starring Will Arnett, and will reportedly only appear in a few episodes next season.

The fifth season of “Glee” will premiere Thursday, Sept. 19, on Fox.