The star, who plays Rachel in Glee, will appear in the show's premiere episode.
Michele confirmed the news on her Twitter page, saying: "So excited to announce that I'll be guest mentoring on the season two premiere of The Glee Project!"
She added: "It was such an amazing experience! All the kids are so talent [sic]! Can't wait for you guys to see it!"
Michele is the first guest mentor to be announced for the second season of The Glee Project. Glee stars who have appeared in previous episodes include Darren Criss, Idina Menzel, Jenna Ushkowitz, Mark Salling and Kevin McHale.
The show, which sees contestants fight it out for a storyline on Glee, was officially renewed last week and filming has started in Los Angeles.
Last year's winner Damian McGinty has already seen his arc on Glee extended past his original seven episodes, while his fellow victor Samuel Larsen is due to make his debut in the Valentine's Day instalment.
The Glee Project will return to Oxygen in the summer.
> Glee Lea Michele with Rachel's dads Goldblum, Stokes Mitchell: Picture