According to the 5th-century historian, Paulinus, Venerius was a deacon and he was present at the death of Ambrose in 397.

[2] Venerius is also known from a letter written to him by Pope Anastasius I concerning the condemnation of the ideas of the Origenists.

[2] In 404 Venerius, along with Pope Innocent I and Chromatius, bishop of Aquileia, took a stand in favour of St. John Chrysostom who has been unjustly banned from Constantinople, writing in his favour to Honorius, the Western emperor, who sent this letter to his brother, Arcadius, the Eastern emperor.

[2] Venerius died on May 4, 408, and he was buried in the Church of Saint Nazarius and Celsus in Milan.

[3] A late tradition, with no historical basis, associates Venerius with the Milan's family of the Oldrati.