William A. Libbey was born on March 27, 1855, in Jersey City, Hudson, New Jersey, a son of William Libbey (1820-1895), a wealthy New York City merchant, and Elizabeth Conklin Marsh (1825-1907), and a brother of Jonas Marsh Libbey (1857-1922), a businessman and editor and proprietor of the Princeton Review.

He was an American professor of physical geography at Princeton University. After graduating from Princeton in 1877, where he was responsible for the adoption of orange and black as the school colours, he went on the Princeton scientific expedition to the West. He continued his studies in Berlin and Paris and in 1879, he received his doctorate in geology from Princeton University. In 1880, he was appointed as director of the Elizabeth Marsh Museum of Geology and Archaeology as well as an associate professor of physical geography. In 1883, he became a full professor and continued to teach physical geography classes. In the 1912 Summer Olympics, he won the silver medal as a member of the U.S. Olympic Rifle Team. He also served as a president of the American Rifle Association and was a colonel in the New Jersey National Guard.

In 1880, he married Mary Elizabeth Green (1859–1931). He died on September 6, 1927, in Princeton, Mercer, New Jersey.