Raised in suburban Rossville, she graduated from Kenwood High School. Gillette studied at the Peabody Conservatory and made her Broadway debut in Gypsy in 1959.
She is notable for her extensive Broadway credits, her many appearances as a celebrity guest on television game shows, her guest-starring and recurring roles in American television series and for her roles in feature films. In 2012, she played Rose Fitzgerald (Mom) in Christmas with the Fitzgeralds, written, directed and starring Edward Burns.
Married Ronald William Gillette, October 13, 1957 (divorced 1967). Children: Timothy Ronald, Chrisopher John. Married Armand Eugene Coullet, July 23, 1982.