Christian lawyer in Constantinople whose church history, distinguished for its classical literary style, its favouring of monasticism, and its greater use of western European sources, rivaled that of his elder contemporary Socrates Scholasticus.

Dedicating the project to the reigning Byzantine emperor, Theodosius II (408–450), Sozomen compiled his work in nine books to cover the period 324 to 439. The surviving text, however, ends at 425, raising the question of whether the final part was suppressed or lost.

Sozomen possibly intended to recast Socrates' work in a superior literary style for an audience not only of ecclesiastics but also of the cultured laity. Although he demonstrated less critical method and limited theological comprehension, Sozomen's unique inclusion of certain sources makes his work valuable in itself and as a corrective of Socrates' text. His work had lasting influence through the translation of excerpts of his history and that of Socrates, Cassiodorus, and Epiphanius in the 6th century, which provided the medieval church with most of its knowledge of this period of Christianity.