He was born on October 18th, 1911 in the village of Miciūnai, Gervėčių Parish (currently Belarus). After he completed his studies at Vytautas the Great High School in Vilnius, he entered the seminary in 1930. He was ordained a priest in 1936. During his assignment as vicar in Rodūnė, he was persecuted by Polish officials, because he defended the rights of Lithuanians. From 1939, he was a pastor in Palūšė, Naujasis Daugėliškis, and Adutiškis. In 1955, he was appointed Bishop of Antarada and Auxiliary Bishop to Bishop Kazimieras Paltarokas. After the consecration, Bishop Julijonas Steponavičius transferred to Vilnius. In 1957, the Apostolic Throne granted him apostolic administrative powers with the rights of bishop in residence. On January 3, 1958, he assumed these responsibilities after the death of Bishop Paltarokas. He refused to abide by the orders of Soviet officials, who demanded that youth not be allowed to participate in church activities. He was exiled to Žagare in 1961, because of his actions. On December 28, 1988, he was finally allowed to take on his duties as the Apostolic Administrator in the Archdiocese of Vilnius. On February 7,1989, he was appointed Archbishop Ordinary by Pope John Paul II. Archbishop Julijonas Steponavičius died in Vilnius on June 18, 1991.