Ruth Firestone was born in Minnesota to a Jewish-American family with roots in Germany and Alsace on her mother's side and Hungary on her father's side. Both parents were Reform Jews and very active in the local Jewish community. Ruth graduated Phi Beta Kappa from Vassar College in 1941. That same year, she married Howard Brin, and while he served in the U.S. Army during World War II, she worked for the War Production Board in Washington, D.C. The couple returned to Minnesota after the war and had four children.
Ruth Brin earned a master's degree in American studies from the University of Minnesota in 1972. Ruth Brin was a pioneer of American Jewish liturgy development in the post-war era. In the 1950s, when most Jewish women still played traditional subordinate roles in public worship, she was modernizing traditional Jewish prayers and texts, providing new interpretive readings and original poetry. Today most prayer books and anthologies in the United States and Canada contain her writings, and many individual synagogue services make use of her work. In a writing career that spanned more than 50 years, Ruth Brin produced four books of poetry and prayers, five worship services, five children’s books, and dozens of scholarly and historical articles, as well as librettos published in "The Hush of Midnight" (1970) and "Kristallnacht" (1988). In 1966, she founded Identity, a Jewish literary magazine, and edited it for five years.
She taught Jewish Studies at the University of Minnesota and Macalester College and wrote book reviews for the Minneapolis Star Tribune. She served on numerous boards of directors, including those of the Minneapolis Urban League, the League of Women Voters, and Hadassah. She was a co-founder and board member of Mayim Rabim, a Reconstructionist synagogue in Minneapolis. She chaired the Head Start program for children in her area, and volunteered to work with young children at a day care center.
Ruth Brin received an honorary degree from the Reconstructionist Rabbinical College in 1985. In 1998, she wrote a memoir about growing up Jewish in Minnesota in the 1920s and 30s; in 2008, at the age of 86, she published her first novel.