Harris acted in community theater after marrying and having three children. She recalled in 1995 that she did 27 national spots in one year. Her agent said that she found fame as Estelle Costanza, a role that shared her name. She bickered with her husband, Frank, voiced her disappointment in her son, and nagged and screeched her way through nine seasons of the show.

They yell at me whenever I walk down the street. You are just like my mother. She told the Pittsburgh Post-Gazette in 1998 that she is the mother that everybody loves, even though she is a pain in the neck.

The high-pitched voice that made Harris cut through the jokes and laugh track of Seinfeld gave her a career in animation. She voiced Old Lady Bear in Brother Bear and Mrs. Potato Head in the Toy Story movies. There was a recurring role on The Suite Life of Zack and Cody.

She told the Canadian Press in 2012 that she thought those roles would get her younger fans. Even the younger generation still knew her best.

She said that she believes that the show will go on for many years because of the writing and cast.

She has three children, three grandsons, and a great-grandson.