He was born in Philadelphia and educated at the Franklin Institute in that city. After his father's death in 1832, he made his début a week later at the Arch Street Theatre in Philadelphia in the part of Young Norval, the character in which his father, also an actor and also named William Warren, had begun his career upon the stage.
He first appeared in New York City in 1841, in London in 1845, and in Boston in 1846. He played in various characters, from broad and eccentric comedy to juvenile tragedy, with general acceptance. His semicentennial in 1882 brought out many deserved tributes to an admirable comedian and representative of the best traditions of the stage.
Toward the last Warren was particularly successful in rendering the roles of fine old English gentlemen. He was a cousin of Joseph Jefferson. He was at his best in such roles as Dr. Pangloss in The Heir at Law, Sir Peter Teazle in The School for Scandal, Dr. Primrose and Touchstone in As You Like It.
In December 1853, Warren was accused of shooting Singleton Mercer, a man who had been the subject of a sensational murder trial fictionalized in George Lippard's The Quaker City (Daily Gazette, Utica, NY, 30 December 1853). Warren was never charged in the case, and Mercer ultimately recovered. He died in Boston.
The next year, in 1847, he became a member of the Boston Museum, where he remained, with a brief exception, until he retired in 1883.