While the name of Philip's mother is unknown, he did have a brother, Gaius Julius Priscus, an equestrian and a member of the Praetorian Guard under Gordian III (238–244). In 234, Philip married Marcia Otacilia Severa, daughter of a Roman Governor. They had three children, a son named Marcus Julius Philippus Severus (Philippus II), born in 238, a daughter called Julia Severa or Severina who is known from numismatic evidence but is never mentioned by the ancient Roman sources and a son named Quintus Philippus Severus, born in 247.