Legio XXII Deiotariana was levied in 48 BC by Deiotarius the king of the Galatians, client of Rome.

After the accession of Augustus to the throne, XXII Deiotariana is allocated to Alexandria in Egypt, where it shared camp with Legio III Cyrenaica at least until 119. The main tasks were to keep peace among the several ethnies that lived in the country and suppress attacks from the desert tribes of the South.

During the civil war of the year of the four emperors, XXII Deioteriana supported Vespasian, that eventually would become the sole victor.

After 119, there are no more records from this legion, presumably destroyed during the jewish rebellion of 132-136

See also: List of Roman legions, Roman legion