His father was Jenő Hirth, and his mother was Rozana Huber; they emigrated to the United States at an unknown date. He completed his elementary education in Újpest and his secondary education in Mátyásföld, and then became a seminarian in Vác. He was ordained a priest in Vác by Diocesan Bishop Dr. József Pétery on July 15, 1945.

In 1948, he served as an assistant pastor in Lajosmizse, and from 1949 to 1950, he served as parish priest in Hernád. During the communist persecution of the Church in the 1950s, he was subjected to harassment by the ÁVH. A memoir written by Miklós Furiakovics lists the priests with whom he was imprisoned at the Vác prison and the Kozma Street detention center, and Hirth is among them. Hirth was sentenced to five years in prison for the crime of incitement, a ten-year ban from public office, and the confiscation of half his assets. He was released from the Vác prison on September 24, 1953—after his sentence was reduced to one-third due to a presidential pardon—and moved in with his relatives at 3 Csokonai Street in Újpest.
In 1965, he applied to emigrate to the United States for the purpose of family reunification, which Dr. Vince Kovács, an ordained bishop, the Apostolic Administrator of Vác, granted him permission to do so, releasing him from the diocese on the condition that he either find a host bishop or apply to the Consistorialis Congregatio for a one-year residence and ministry permit for the purpose of visiting relatives. He listed Gyömrő as his last address in Hungary. He arrived in the United States on September 26, 1965, aboard the ship Bremen. He then moved in with his family in Chicago, IL, and celebrated Mass at the local St. Gertrude Church. He registered with the archdiocese, and the archbishop sent his documentation to Rome for verification. At the same time, he studied English at the Berlitz School of Languages.
The Catholic Committee for Refugees assisted him in settling in the United States; extensive documentation of this process has been preserved. He initially intended to settle in the Archdiocese of Chicago, but the archdiocese did not accept immigrant priests; however, it granted him permission to remain within the archdiocese’s territory for six months, with the approval of the Sacred Congregation of the Consistory.
Later, the Diocese of Albany accepted him, and he served as a priest there.

According to some sources, he later left the priesthood and started a family. According to MyHeritage.com, his wife’s name was Helen Karancz. There is no information about his later life, or the place and date of his death.