Mabel Rosalie Barrow was born on November 3, 1877, in a brownstone on New York City's Gramercy Square. She was born into a well-off family, led by her father John Wylie Barrow and her mother Harriet. Her father prospered as an importer and as an accountant, having already been attached to the British Embassy in Rome, Italy. Despite her father's death in 1887 and the financial losses that derived from it, Rosalie Barrow was well-educated at Miss Doremus' School. She regarded her inability to go to college a "major deficiency," in the words of her son, and thus she cherished the honorary degrees she was given after coming to prominence. While on a trip to England at the turn of the century she met her future husband. After a suitable courting period, Rosalie Barrow married Charles Noel Edge at Christ Church in Yokohama, Japan, on May 28, 1909.

On a trans-Atlantic trip, Edge met a woman who became very important in her life, Margaret Haig Thomas, Viscountess Rhondda. The founder of the magazine Time and Tide, Lady Rhondda was a prominent women's suffrage activist. The days spent aboard ship with Lady Rhondda had a profound effect on Edge. Upon her return to the United States, she became a powerful force in the American movement, which culminated in the passage of the 19th Amendment in 1920.

After the women's suffrage cause was won, Rosalie Edge spent a number of years in high society and became a passionate "birder," accumulating a life list of 804 species. She even telegramed her son Peter at school to tell him to stop at New York's Central Park to see a loon in the pond. Her passion was accelerated in 1929 when she received a pamphlet written by Willard Van Name called "A Crisis in Conservation." The pamphlet particularly attacked the National Association of Audubon Societies (NAAS) for allowing hunting on the land it owned in Louisiana. As a life member of that organization, Edge was incensed and began to work to reform the Conservation movement. After meeting Dr. Van Name, she formed the Emergency Conservation Committee, and in a little over three years, she had hounded the officers of the NAAS from their posts. Her Emergency Conservation Committee published numerous pamphlets through the years.

Rosalie Barrow Edge's longest lasting legacy began in 1932. She and the rest of the conservation movement saw pictures taken by Richard Pough of hawks dying in the Kittatinny Mountains of eastern Pennsylvania. She first attempted to get the Audubon Society to buy what later became known as Hawk Mountain, but she failed. She then began a year-long campaign to raise the $3,500 necessary to purchase the site. On New Year's Eve 1932, she successfully founded the Hawk Mountain Sanctuary near Kempton, Pennsylvania. The association Edge founded runs the Sanctuary today, saving birds, conducting research, and running educational programs.

Rosalie Barrow Edge died on November 30, 1962, at the Columbia-Presbyterian Medical Center in New York City. With her death, the work of the Emergency Conservation Committee ceased, but the work of the Hawk Mountain Sanctuary she founded continues on today.