Haupt was born in Chicago to Sadie and Moses Annenberg, the founder of a publishing empire based on The Daily Racing Form and The Philadelphia Inquirer. She was fourth of eight children and last surviving child (seven girls and a boy) born to the couple; the boy was Walter H. Annenberg, who was to become a publisher and philanthropist in his own right. One of her sisters was Janet Annenberg Hooker. She grew up in Milwaukee.
She was tall and thin as a young girl, and resolved to impress her older sisters by memorizing a new word each day. She attended Mount Ida Seminary in Newton, Massachusetts, during which time her family moved to New York. Her father was convicted of tax evasion during the 1930s and sentenced to two years in prison; he died in prison.
In 1953, she was charged with publishing Seventeen magazine, a post she would hold until 1970. She also wrote "Young Living", a syndicated fashion, beauty and lifestyle column.
Haupt's first marriage, to Norman Bensinger, ended in divorce; they had one child, Pamela Enid Bensinger (Nusbaum, Allen), (1929-1997). She later married Ira Haupt, who died in 1963. It was through this marriage that she became involved with gardening, particularly in the growing of flowers, after she encouraged her husband to help his gardeners find better jobs.
Haupt is quoted as often having said "Nature is my religion," and once told The New York Times "Books are the most important things in my life besides nature." As an heiress to a family fortune, she was able to make significant contributions to her personal causes and interests, foremost among which was horticulture.
Haupt contributed the Haupt Fountains at the Ellipse located between the White House and the Washington Monument, and also a four-acre Victorian garden, known as the Enid A. Haupt Garden, on the south side of the Smithsonian Castle. The Enid A. Haupt Garden at the Smithsonian is intended by its architect, Jean Paul Carlihan, to interpret nearby museums. It is situated atop the underground portions of the Quadrangle building, which includes the National Museum of African Art, the Arthur M. Sackler Gallery (Asian art), and the S. Dillon Ripley Center. Accordingly, the end of the garden nearest the African Art museum contains a modern interpretation of an Islamic garden, and the end nearest the Sackler Gallery is accented with pink granite moongates.
She donated River Farm, a 27-acre plantation, located near Mount Vernon and once owned by George Washington, to the American Horticultural Society. A Victorian style conservatory located in the New York Botanical Garden was saved from demolition through her efforts and funding. She spent large sums over the years to maintain the gardens of The Cloisters, part of the Metropolitan Museum of Art. She contributed to the garden of Claude Monet in Giverny, France, and to Lady Bird Johnson's National Wildflower Research Center.
Among her other contributions are works of art for the Metropolitan Museum of Art and the National Gallery of Art, and funding for the Memorial Sloan-Kettering Cancer Center. According to The New York Times, "The gift that gave her the most satisfaction, she said, was one of her earliest and least heralded: the Enid A. Haupt Glass Garden, a playground for children who are patients at the Rusk Institute of Rehabilitation Medicine at New York University Medical Center."
Enid Haupt died at age 99 at her home in Greenwich, Connecticut.