William Branford Shubrick was born on October 31, 1790, at "Belvedere Plantation," Bull's Island, South Carolina (now an undeveloped barrier island within the Cape Romain National Wildlife Refuge), to Mary Branford and Colonel Thomas Shubrick, William was the sixth son and ninth child of the family of sixteen.

He briefly studied at Harvard College in 1805-1806 before being commissioned a midshipman on June 20, 1806 at the age of sixteen joining his older brother, John Templer Shubrick.

During the subsequent decades before the Mexican–American War, Shubrick commanded, in turn, Lexington and Natchez; directed operation of the West Indies Squadron from 1838 to 1840; and headed the Bureau of Provisions and Clothing from 1845 to 1846.

At the outbreak of the war with Mexico, Shubrick requested sea duty and, in Independence, sailed for the California coast to relieve Commodore John D. Sloat in command of American Naval forces there.

However, Commodore James Biddle brought his East India Squadron to Monterey, California, on 2 January 1847 only a week after Shubrick's arrival, and assumed command.

He was promoted to rear admiral on the retired list on 16 July 1862 and for ten years served as chairman of the United States Lighthouse Board where he was a member since 1852.