Philip Wilson, the archbishop of Adelaide, is expected to be sentenced by the court in June. He faces a maximum penalty of two years in jail.
He was accused of covering up a serious indictable offence by another priest, James Fletcher, after being told about it in 1976 when he was an assistant parish priest in the state of New South Wales. Lawyers for Wilson, 67, had argued that he did not know that Fletcher had abused a boy, media reported.
Fletcher was found guilty in 2004 of nine counts of child sexual abuse and died in jail in 2006.
An emailed statement from the local court in Newcastle, New South Wales, said Magistrate Robert Stone ruled the “offence proven.”
Stone said he did not accept that Wilson could not remember a conversation in 1976 in which the victim, who would have been 15 at the time, had described how he was abused by Fletcher a few years earlier, according to media reports.
Last year, Australia completed a five-year government-appointed inquiry into child sex abuse in churches and other institutions, amid allegations world-wide that churches had protected paedophile priests by moving them from parish to parish.
The inquiry heard that 7 percent of Catholic priests working in Australia between 1950 and 2010 had been accused of child sex crimes and that nearly 1,100 people had filed child sexual assault claims against the Anglican Church over 35 years.