According to TV Line, which first broke the news Monday (Aug. 19), the actress-singer will appear in at least six episodes as Dani, a struggling artist in New York City who is friends with both Rachel (Lea Michele) and Santana (Naya Rivera).
She is also expected to share some significant screen time with the new character played by "American Idol" alum Adam Lambert, including several musical numbers.
Lovato will first appear in the second part of the FOX musical's tribute to The Beatles, airing on Oct. 3, which is the second episode of the upcoming fifth season. The series will air three episodes in the fall, including a tribute episode to the late Cory Monteith, and will return sometime later in the season.
This marks Lovato's first major acting role since starring in the Disney Channel's "Sonny with a Chance." Her other TV credits include the "Camp Rock" movies, "Prison Break" and "Grey's Anatomy."
She returns for her second season as a judge on "The X Factor," which airs its results show before "Glee" on Thursdays this fall.
"Glee" Season 5 premieres on Thursday, Sept. 26 at 9/8 p.m. CT on FOX.