Born in Lexington, Virginia, Mann was the third of three children and the only daughter. Her father, Robert S. Munger, was a general practitioner, and her mother, Elizabeth Evans Munger, ran the bookstore at Washington and Lee University in Lexington. Mann graduated from The Putney School in 1969, and attended Bennington College and Friends World College. She earned a B.A., summa cum laude, from Hollins College (now Hollins University) in 1974 and a M.F.A. in creative writing in 1975. She took up photography at Putney, where, she claims, her motive was to be alone in the darkroom with her then-boyfriend. She made her photographic debut at Putney, with an image of a nude classmate. Her interest in photography was promoted by her father. His 5x7 camera became the basis of her use of large format cameras today.
Mann has three children: Emmett, born in 1979, Jessie (herself an artist, photographer and model) born in 1981, and Virginia born in 1985. Mann lives on a farm in Virginia with her husband, Larry. He is a full time attorney, and has muscular dystrophy, with progressive weakness. Mann is passionate about endurance horse racing. Mann is currently represented by the Gagosian Gallery of New York City.
Her works are included in the permanent collections of the Metropolitan Museum of Art, the Corcoran Gallery of Art, the Hirshhorn Museum and Sculpture Garden, the Museum of Fine Arts, in Boston, the San Francisco Museum of Modern Art, and the Whitney Museum of New York City among many others.
Time magazine named Mann "America's Best Photographer" in 2001. Photos she took have appeared on the cover of The New York Times Magazine twice: first, a picture of her three children for the September 27, 1992 issue with a feature article on her "disturbing work," and again on September 9. 2001, with a self-portrait (which also included her two daughters) for a theme issue on "Women Looking at Women."
Mann has been the subject of two film documentaries. The first, Blood Ties, was directed by Steve Cantor, debuted at the 1994 Sundance Film Festival, and was nominated for an Academy Award as Best Documentary Short. The second, What Remains was also directed by Steve Cantor. It premiered at the 2006 Sundance Film Festival and was nominated for an Emmy for Best Documentary in 2008. In her New York Times review of the film, Ginia Bellafante wrote, "It is one of the most exquisitely intimate portraits not only of an artist’s process, but also of a marriage and a life, to appear on television in recent memory."
Mann received an honorary Doctor of Fine Arts degree from the Corcoran Museum in May 2006.