Martha Scott became interested already in the high school for acting. So she studied drama at the University of Michigan in Detroit. Her professional stage debut was in 1933/1934 Shakespeare productions at the World Exposition in Chicago. Then she moved to New York to play at the Broadway Theater. During a performance of the play Our Town by Thornton Wilder, in which she played the female lead role of Emily Webb, she was discovered for the film.

In Hollywood, which played the same role in 1940 in the film adaptation of the play by Sam Wood and received a Oscar nomination. It was the only one during their careers. In the multi-Oscar winning film, with Ben-Hur, she played the role of Miriam, the mother of the title character, who was portrayed by Charlton Heston. During her subsequent career, she was working both for the film as well as in the theater. In 1968 she joined at the Plumstead Theater Company Theater production of Henry Fonda and Robert Ryan.

Martha Scott was married from 1946 until his death in 1998 with the jazz pianist and composer Mel Powell. In 2003 she was buried in her hometown of Jamesport on the side of her husband.