Philip Wilson, the archbishop of Adelaide, becomes the most senior Catholic in the world to be charged and convicted of the offence.
He was found to have covered up the abuse of altar boys by a paedophile priest colleague in New South Wales.
During his trial he denied being told about the abuse by some of the victims.
In a statement issued by the church on Wednesday, Wilson said he was "obviously disappointed" with the verdict and would consider his legal options.
