Born in Sturgis, Michigan (official records say 1909 but MacCloy claimed they confused her with her older sister and she was actually born in 1915), MacCloy moved to Toledo, Ohio as a child. In 1928 she joined Earl Carroll's Vanities but her mother forced her to quit due to her skimpy costume. She soon had a part in George White's Scandals, impersonating co-star Harry Richman on the song I'm on the Crest of a Wave, and later appeared in a vaudeville troupe designed by Vincente Minnelli, whom she viewed as "sadistic". In 1930 she began making films, signing a contract with Paramount Pictures in 1931. She was loaned out for the musical comedy Reaching for the Moon, starring Bebe Daniels and Douglas Fairbanks. In 1932 she appeared in Florenz Ziegfeld's last production, Hot-Cha. When that closed she toured with a band in a variety of major cities and sang on the cruise ship S.S Transylvania, but radio producers were not interested in her voice.

MacCloy appeared in a variety of short films (including some directed by the disgraced Fatty Arbuckle) and some features with stars such as Zasu Pitts, and she had her share of admirers (one man offered to take her on a flight in a plane full of rose petals), but never gained any traction. MacCloy's last major role arrived in 1940, when she sparred and flirted with Groucho Marx in one of the Marx Brothers' final films, Go West. Groucho asked her to appear in another film, but she declined, claiming she wanted to make serious pictures.

In December 1941 she married architect and fellow jazz enthusiast Neal Wendell Butler, with whom she raised two children until his 1985 death. MacCloy had few regrets about her failure as an actress, but years later wondered if film producers had shied away from her due to their assumption that she was a lesbian.

MacCloy died May 5, 2005 of natural causes.