During a bohemian childhood spent solely in the company of a governess and her artist parents, Margaret Frances "Peggy" Bacon lived first in the US, then the Bahamas, England, and France all before the age of fourteen. Her parents did not believe in formal schooling, so she was encouraged only to study what interested her. By her description, her unconventional childhood was "absolutely delightful."

By 1915, she was enrolled at the Arts Students League in New York. Among her classmates were John Sloan, Kenneth Hayes Miller, and George Bellows.  In 1917, after discovering there were no etching classes offered, she taught herself, capturing her unique drawing style with drypoint. This technique would be her primary medium for the next ten years.  Shortly after, while studying with Andrew Dasburg in 1919, she met Alexander Brook, her husband for twenty years, and father to her two children.

With a career launched in her early twenties, she would go to illustrate more than 60 books, in addition to creating print editions and pastels. Published frequently in The New Yorker and Vanity Fair, her elegant, satirical caricatures were widely admired. Her first solo exhibition was at Alfred Stieglitz Intimate Gallery. Throughout her career, she would have more than 30 one-woman shows. She received a Guggenheim award in 1934, and in 1975 the National Museum of American Art honored Bacon with a year-long retrospective titled Peggy Bacon: Personalities and Places.

By the 1970s, Bacon's eyesight had begun to fail, and she retired to Maine, where she lived until 1987.