Information about the life of Pertinax are present in the history of Dorotheos. There it is mentioned that Pertinax was a high-ranked officer of the Roman Empire, who was sent to Thrake as a commander.

When he suffered some kind of illness, he learned that several miracles happen among the faithful of the new religion, Christianity. This led him to ask the bishop of Byzantium, Alypius, who was then staying at Elaia. After his healing, which he attributed to the prayers of Alypiuw, he denounced the national religion and was baptised a Christian.

After a short period of time, he was ordained a Presyter by Alypius, whom after his death succeeded in the bishopric throne. From his own property, he built the thirst bishopric house of the Church of Byzantium in the area of Sykeon (which is now known as Galata), by the sea, at a place he named Irene (=peace). In this area, several Christians started building their houses, creating thus a small city.

The patriarchical lists have his as a Bishop of Byzantium for 19 years (169–187), but probably these include the years during which he was a priest. He fell asleep in 187.