Born in Rochester, New York, he was raised with the combination of his grandparents' traditional Jewish piety and his father's modernist socialism. He graduated as valedictorian of his class at DeWitt Clinton High School and then majored in Classics at City College of New York which he graduated from summa cum laude in 1924. Steinberg received his doctorate in philosophy from Columbia University in 1928 and then entered the Jewish Theological Seminary of America were he was ordained. In seminary, he was strongly influenced by Rabbi Mordecai Kaplan (1881–1983), the founder of Reconstructionist Judaism.
After five years in a pulpit in Indiana, he was invited by the Seminary to assume the pulpit of Manhattan's Park Avenue Synagogue, then a small congregation with a Reform orientation. In his sixteen years at the congregation, he grew it from 120 to 750 families. In 1943 he had a near fatal heart attack.
Steinberg's works included Basic Judaism, The Making of the Modern Jew, and As A Driven Leaf, a historical novel revolving around the talmudic characters Elisha ben Abuyah and Rabbi Akiba. In his final years, he began writing a series of theological essays. This project, which he had hoped would conclude in a book of theology, was cut short by his death at age 46.
- The Making of the Modern Jew (1934)
- As a Driven Leaf (1939)
- A Partisan Guide to the Jewish Problem (1945)
- A Believing Jew (1951)
- Anatomy of Faith (1960)
- Basic Judaism (1965)
- Noveck, Simon, "Milton Steinberg" in Kessner, Carole S., The "Other" New York Jewish Intellectuals, New York University Press, 1994.
- "RABBI STEINBERG DIES AT AGE OF 46", New York Times (1857-Current file); Mar 21, 1950; ProQuest Historical Newspapers The New York Times (1851 - 2005) pg. 29