Born in Castelvetrano, Province of Trapani, Sicily, Mariano Crociata was ordained as a priest in 1979. He studied philosophy and theology at the Pontifical Gregorian University of Rome, where he was awarded a doctorate in theology in 1984.
He ran the theology of religions department at Palermo's Theological School. From 2003 he was vicar general of the Diocese of Mazara del Vallo.
On 16 July 2007 Pope Benedict XVI appointed him Bishop of Noto. He was consecrated on 6 October 2007. On 26 September 2008 Pope Benedict appointed him secretary general of the Italian Bishops’ Conference (CEI).
He is the bishop of the Diocese of Latina-Terracina-Sezze-Priverno since 19 November 2013. He is the delegate of the Italian Bishops conference to COMECE since 2017.