William Scott was born around 1839 in Albemarle County, Virginia. His owner, John Coles Carter, migrated from Virginia to Missouri in 1852 and owned 126 slaves on multiple plantations by 1860. Scott worked as a laborer on one of Carter's farms in Missouri during the late antebellum era. He enlisted as a private in the Union army on November 30, 1863, and mustered into Company K of the 60th USCT Infantry Regiment at Benton Barracks in St. Louis. His enlistment records describe him as 5 feet, 7 inches tall, with black hair, black eyes, and a black complexion. Scott served throughout Arkansas, taking part in a skirmish at Wallace's Ferry on July 26, 1864. In July 1865, he was detached on escort duty. He mustered out on October 16, 1865, in DeValls Bluff, Arkansas.

Following the war, Scott settled in Paynesville, Missouri. He married Priscilla Carter in Paynesville in 1868, and they no children together. Scott died in Paynesville in the summer of 1873 from cholera. Following his death, his widow Priscilla moved to Quincy, Illinois. Although she applied for a pension, she did not receive one, because the government determined that she and Scott had never gotten legally married.