Petar Kočić was born into a Bosnian Serb family in the hamlet of Stričići, in the Zmijanje region near Banja Luka, northern Bosnia, on 29 June 1877.
Kočić left Gomionica after two years and completed his primary education at the Eastern Orthodox religious school in Banja Luka, though he returned to the monastery every summer in order to spend time with his father.