Born in Germantown, Pennsylvania, Anna Mary Richards Brewster was the daughter of noted marine and landscape painter, William Trost Richards whose reputation eclipsed hers. However, she earned a prestigious reputation as an active professional artist for fifty-five years. Her early work reflected the tight detailing of her father's style, but as she learned to paint faster, her canvases became looser and looser in style, and many have a warm tonality and atmosphere.

She learned painting technique from her father and by age fourteen was exhibiting at the NationalAcademy in New York City. In 1888, she studied at the Cowles Art School in Boston under Dennis Bunker and later studied in New York with John LaFarge and William Merritt Chase. She studied in Paris at the Academy Julian and then made her home in England for nine years. She also painted throughout Europe, Egypt, Palestine, and North Africa.

She married William Tenney Brewster, professor at Barnard College, and in 1910, the couple settled in Scarsdale, New York, where she founded the Scarsdale Art Association. The couple spent their summers at a family cottage in Matunuck, Rhode Island and traveled together extensively in Europe and North Africa. On these trips, she did numerous oil and watercolor sketches, which she converted into large canvases.