According to ew.com, Lynch has recorded vocals for Roz, an assistant of Homer's at the Springfield Nuclear Power Plant who turns out to be after his job. The episode will air early next season.
Lynch, whose numerous film credits include "Julie and Julia," "The 40-Year-Old Virgin," and "Best in Show," recently appeared Off-Broadway in Love, Loss and What I Wore.
"The Simpsons" airs Sundays at 8 PM ET, and "Glee" airs Tuesdays at 8 PM ET on Fox.