Rosamond Pinchot was born in New York City. At the age of nineteen, Pinchot was discovered by Max Reinhardt while traveling on an ocean liner with her mother. Reinhardt cast her as a nun who runs away from a convent in the Broadway production of Karl Vollmoller's The Miracle. Reinhardt later cast her in productions of William Shakespeare's A Midsummer Night's Dream and Franz Werfel's The Eternal Road. She made her only film appearance in the 1935 adaptation of The Three Musketeers, as Queen Anne. Pinchot married William "Big Bill" Gaston.
On the morning of January 24, 1938, a cook found Pinchot's body in the front seat of her car parked in the garage of a rented estate in Old Brookville, New York. Her death was later determined to be caused by asphyxia due to carbon monoxide poisoning and was ruled a suicide.