Struck By Lightning, which stars and was penned by Glee actor Chris Colfer, follows a manipulative teenager who blackmails his high school classmates into contributing to his literary magazine and is eventually killed by a bolt of lightning.
Janney will play the mother of Colfer's character, reports Variety.
Colfer also expressed his excitement at the casting via his Twitter page, writing: "Struck By Lightning news!!! Allison Janney is my mum!!! I couldn't be more thrilled!"
Struck By Lightning will begin filming on July 11 in Los Angeles, with no release date currently set.
Colfer recently inked a deal with Little Brown Publishing to write his own book of fairy tales, The Land of Stories, which will hit shelves in 2012.
He has also secured a development deal with the Disney Channel for his series The Little Leftover Witch, based on a children's book by Florence Laughlin.