He served as Praetorian prefect of the East, of Italy, and of Gaul.
Probably born in Rome, he was notarius under Emperor Valentinian I when, in 365, he was sent to Africa to guarantee the loyalty of that province during the usurpation of Procopius, who had rebelled against the eastern Emperor Valens.
Putting Neoterius in charge of the Italian prefecture, Theodosius I wanted to support the young and inexperienced Emperor Valentinian II from the influence of the Western usurper Magnus Maximus.
[1] Neoterius is probably to be identified with the prefect who wanted to give the basilica Portiana of Milan to the Arians but who was opposed by the Nicene bishop Ambrose.
In 390 he was Praetorian prefect of Gaul, as well as consul with the Emperor Valentinian II as colleague; this appointment can be seen as protecting Theodosius' interests in Gaul.