Born into a family of Russian Jewish immigrants in Denver, Colorado, in 1916, Ruth Moskowicz married her high school sweetheart Elliot Handler in 1938. They eventually moved to Los Angeles and had Amid Ken. In the midst of World War II, the Handlers founded Mattel. While vacationing in Europe in 1956, Ruth Handler's daughter Barbara, then 15 years old, brought her attention to a plastic doll with adult proportions and the ability to be dressed in various outfits based on the German comic strip character Bild Lilli, the doll which inspired Handler to create and launch Barbie and Ken a few years later.

In the early 1970s, Ruth was diagnosed with breast cancer and underwent a mastectomy. As a result of her illness, she created Nearly Me, a line of prostheses that she defined as "more real."

Handler passed away following a surgery for colon cancer in 2002.