Nicolás Alessio was suspended in 2010 when the Government’s same-sex marriage legislation was being debated.
The legislation was bitterly opposed by the Church in Argentina, led by the then Cardinal Jorge Bergoglio who was elected Pope last month.
A statement from Mr Alessio’s local archdiocese of Córdoba said the decision to defrock him was made by the Vatican’s Congregation for the Clergy in February, during the pontificate of Benedict XVI.
“Thirty years of service to God’s people mean nothing,” Mr Alessio said in response. “I had a different opinion from the archbishop [of Córdoba, Carlos José Ñáñez] and so they have chucked me out.”