Gardner was born in Marinette, Wisconsin, and moved to Los Angeles after finishing high school to join her brother, the producer Arthur Gardner, who at the time was working as an actor in film and theatre.
After graduating from UCLA she started out as a magazine writer and went on to become vice president in charge of international affairs for Rogers & Cowan.
She handled publicity on many films including Darryl F Zanuck's The Longest Day. As a personal publicist, her client roster included Audrey Hepburn, Kirk Douglas, Shirley MacLaine, Cary Grant, Peter Ustinov, Rex Harrison, and Elizabeth Taylor.
As international head of Rogers & Cowan based in London and Paris for more than 30 years, Gardner became a fixture at the Cannes Film Festival, which honoured her in 1991.
She leaves behind her brothers Arthur and George, sister Fay Wallace, and nephews Steven and Douglas Gardner.
At Gardner's request, she has been cremated. In lieu of flowers, she asked donations be made to the Motion Picture & Television Fund.