Sir William Roberts was the son of a surgeon. He studied at University College, London and qualified as a doctor in 1853, and took the MD of the University of London in 1854.He also studied in France and Germany. in 1854 he was appointed a house surgeon at MRI, and shortly after in 1855, became a full honorary physician at MRI. Roberts stayed at MRI until 1883. He also lectured in anatomy and physiology at Manchester Royal School of Medicine. He was later professor of medicine at Owens College (part-time) from 1873-87. He was elected FRCP in 1865, and held a number of offices at the College, including Harveian Orator. Roberts was president of Manchester Medical Society in 1865. He was elected FRS in 1877 and knighted in 1885.
Roberts has a considerable reputation as a medical teacher in Manchester. He was one of the first medical practitioners to emphasise the role of physiology in the treatment of disease. A specialist in renal diseases, he published Practical Treatise upon Urinary and Renal Diseases (1865), which won an immediate reputation for the original way in which it dealt with the subject. In 1889, Roberts moved to London where he spent the last ten years of his life.