William Starbuck Macy was born in New Bedford, Massachusetts. He lived there until 1890, when he moved to Santa Barbara, California. He first studied at the National Academy of Design with William Merritt Chase and Frank Duveneck; he also studied in Munich in the 1870s. He sent a painting to the Paris Salon in 1878. When he returned, he made a trip to the Dakotas, making illustrations for a book by H. Van Dyke.
Macy exhibited his work at the National Academy of Design from 1875-96, the Pennsylvania Academy of the Fine Arts in 1879, 1880, and 1888; the Boston Art Club from 1880-96, the Art Institute of Chicago from 1889-1927, and the Corcoran Biennial of 1937.
His work is in the collection of the New Bedford Whaling Museum.