He wrote 'Jewish Antiquites', a 20-volume history of the Jews from their beginnings to the close of Nero's reign. He is an important source for studies of immediate post-Temple Judaism and the context of early Christianity.

He made references to such figures as Pontius Pilate, Herod the Great, John the Baptist, James the brother of Jesus, and a pair of disputed and undisputed references to Jesus.

He participated in the revolt of Judea against Rome (66-70) and wrote an account of it when he went to Rome after the Jewish defeat.