The show's co-creator and showrunner Ryan Murphy took to Twitter today (April 5) to announce the news.
Murphy also revealed that Sagal will star as Artie Abrams's (Kevin McHale) mother in the show's fourth season.
So thrilled to announce my friend Katey Sagal is playing Artie's mum on Glee! There is nothing this woman can't do!— Ryan Murphy (@MrRPMurphy) April 5, 2013
Responding to the news on Twitter, McHale wrote: "Wooo!" later adding: "Artie's gettin a hot mama."
Meanwhile, Sons of Anarchy creator and Sagal's spouse Kurt Sutter is said to be developing a comedy pilot for FX named Davia. Clown. Killer. Sutter is reportedly interested in casting his wife in the show.