Wallace played teacher Edna Krabappel in 177 episodes of the long-running show. She died Oct. 25 of complications of pneumonia. She was 70.
"We'll really miss you Mrs. K.," character Bart Simpson wrote on the classroom chalkboard in the opening credits of Sunday night's installment, "Four Regrettings and a Funeral."
The Hollywood Reporter said the episode aired after the "Simpsons" classic, "The Ned-liest Catch," which featured Edna dating widower Ned Flanders.