According to The Hollywood Reporter, Griffin will play a character called Tammy, rumoured to be based on former Alaskan Governor Sarah Palin, who will sit on the judging panel for the Regional Glee competition.
The comedienne herself broke the news by tweeting on Friday evening, "So excited!! It's true!!"
Former Grey's Anatomy star Loretta Devine will also appear as a character on the judging panel, as an ex-stripper nun called Sister Mary Constance.
The exact air date of Griffin's guest appearance on Glee is still unknown, although it is likely to be towards the end of the current second season of the Fox sitcom.