Legio I Armeniaca was a pseudocomitatensis legion of the Late Roman Empire, probably created in the late 3rd century. The name of the legion could refer to it being originally part of the garrison of the Armeniac provinces, but the unit, together with its twin legion II Armeniaca, appears to have been included in the imperial field army. The legion took part in the invasion of the Sassanid Empire by Emperor Julian in 363. The Notitia dignitatum records the legion as being under the command of the magister militum Orientis around 400.