He studied at the Jesuit school Zakład Naukowo-Wychowawczy Ojców Jezuitów w Chyrowie.
Born in Huta Komorowska, Austria-Hungary (now part of Poland) in noble family of Ostoja coat of arms, Kozłowiecki was ordained a Jesuit priest on 24 June 1937 after studying at the Zakład Naukowo-Wychowawczy Ojców Jezuitów w Chyrowie.