His father, Marcus Petronius Mamertinus, was suffect consul in 150 and his mother's name is unknown.
Sometime after 173, Cornificia Faustina bore Mamertinus a son, Petronius Antoninus.
Mamertinus and his family could have been at the winter camp of Marcus Aurelius in early 180.
When Marcus Aurelius died later that year, Mamertinus' brother-in-law Commodus succeeded him as Emperor.
Sometime between 190 and 192, Commodus ordered the deaths of Mamertinus, his son, his brother and his sister's family.