Born in Jersey City, New Jersey, Allen worked as a high fashion model for the Ford Agency and appeared as the "And away we go!" girl on The Jackie Gleason Show before making her Broadway debut opposite Peter Ustinov in Romanoff and Juliet (1957). She went on to play major roles in such shows as The Gay Life and Sherry!, also starring in national tours of Cactus Flower and California Suite. Her last stage role was that of Dorothy Brock in the original Broadway and touring productions of 42nd Street.
In Do I Hear a Waltz? -- based on Arthur Laurents' play The TIme of the Cuckoo, which also inspired the Katharine Hepburn film Summertime -- Allen played a lonely American woman who falls in love with a married man while on vacation in Venice. For her performance, she received a Tony Award nomination in the Best Actress category, having previously been nominated for her featured role in The Gay Life.
Her film credits include From the Terrace, Diamond Head, Donovan's Reef, Cheyenne Autumn, Star Spangled Girl, and The Carey Treatment. Throughout her career, Allen appeared in many television variety shows, sitcoms, drama series, variety shows, game shows, and soap operas.
A memorial celebration of her life will be held on October 8 at the Auchmoody Funeral Home in Fishkill, beginning at 11am. In lieu of flowers, donations to The Actors' Fund of America are suggested.