Twomey had recurring roles in the 1993 season of L.A. Law and the 2000-01 season of Third Watch. She has made guest appearances on Shannon (1981 TV series), The Cosby Show, Magnum, P.I., Seinfeld, Spin City, Law & Order, Law & Order: Special Victims Unit, and Law & Order: Criminal Intent, and had a featured role in the 1998 television remake of Rear Window starring Christopher Reeve and Daryl Hannah.