Borthwick earned her BA at the University of Michigan in 1892. She later worked as a librarian in Port Huron, Michigan. In 1899, Borthwick married Edwin Cheney, an electrical engineer from Oak Park, Illinois, USA. They had two children: John (1902) and Martha (1905).
Mamah met Wright's wife, Catherine, through a social club. Soon after, Edwin commissioned Wright to design them a home, now known as the Edwin H. Cheney House, and, as of 2005[update], housing a bed & breakfast.
In 1909, Mamah (now formally known as Martha Borthwick Cheney, although she stopped using her husband's name after they divorced in 1911) and Wright chose to leave their respective spouses and travel to Europe. Upon returning from Europe, most people in their previous social circle considered their open closeness to be rather scandalous, especially since Catherine had refused to agree to a divorce (and wouldn't until 1922). The editor of the local newspaper in Spring Green, Wisconsin condemned Wright for bringing scandal to the village; even big city Chicago papers joined in the criticism, implying Wright would soon be arrested for immorality, despite statements from the local sheriff that he couldn't prove the couple was doing anything wrong. The scandal affected Wright's career for several years. He didn't receive his next major commission, the Imperial Hotel, until 1916.
In 1911, Borthwick began translating the works of the noted Swedish feminist thinker and writer Ellen Key.
On August 15, 1914, one of Wright's recently hired domestic workers, Julian Carlton, murdered Mamah, her two children, three of Wright's associates, and a son of one of the associates. Carlton set fire to one wing of Wright's house, Taliesin, and then he hacked the seven people with an ax while it burned. At the time, Wright was overseeing work on Midway Gardens in Chicago, Illinois.
A detailed nonfiction account of the tragedy at Taliesin is provided in Death in a Prairie House: Frank Lloyd Wright and the Taliesin Murders by William R. Drennan.