She guest starred on DYNASTY in 1982 and appeared in a few episodes of DAYS OF OUR LIVES as Kay Stanhope in 1976.
Singleton met Lucille Ball in the late 1940s during a performance of the radio show "My Favorite Husband"; a few years later, Ball invited Singleton to join the cast of I LOVE LUCY as Carolyn Appleby, Lucy's near-sighted neighbor and sometimes nemesis. She also appeared in several episodes of HERE'S LUCY and was in the 1980 TV movie Lucy Moves to NBC.
Other television appearances included ANGEL, MY THREE SONS, ALL IN THE FAMILY, and many others.
Singleton's husband Charles Isaacs, a comedy writer, director and producer to whom she was married for 61 years, died in 2002.