He was born on October 6, 1816 in York, Maine where his father was the leader of a church choir. He had a brother, Edward G. Bradbury.

He moved with his parents to Boston and met Lowell Mason, and by 1834 was known as an organist. In 1840, he began teaching in Brooklyn, New York. In 1847 he went to Germany, where he studied harmony, composition, and vocal and instrumental music with the best masters.

In 1854, he started the Bradbury Piano Company, with his brother, Edward G. Bradbury in New York City. William Bradbury is best known as a composer and publisher of a series of musical collections for choirs and schools. He was the author and compiler of fifty-nine books starting in 1841.