Ifor Whittaker, 80, admitted rape and gross indecency of a boy in the vestry of St John the Baptist Church in Sedlescombe, East Sussex, where he served as a priest at the time under the name of Colin Pritchard.
The offences are reported to have taken place during the late 1990s when the victim was a young child.
Judge Gary Lucie said Whittaker had baptised him, and that the victim was often left in his care.
He told Whittaker: "You told him... it would be your little secret. Even now he still suffers with mental health issues and had flashbacks.
"There are, in my opinion, serious concerns that you remain a danger to young children," the judge said.
"You are a predatory paedophile, I doubt that you will ever cease to be a danger to young boys."
Whittaker was sentenced on Tuesday at Hove Crown Court.
In 2018, Whittaker was jailed for 16 years for sexually abusing a boy and conspiring with another priest to abuse the child.
At the time of that sentencing, the judge said the abuser had "plied the victim with alcohol" and "emotionally blackmailed the boy by saying 'no one would believe you over a priest'".
He had previously been jailed for five years in 2008 for the abuse of two children in Wellingborough, Northamptonshire, between 1979 and 1983.
A spokesperson for the Diocese of Chichester said its safeguarding team had worked closely with Sussex Police on the case since it was reported.
They said the sentence reflected "the terrible nature of his crimes".
"The victim in this case has shown extraordinary courage in coming forward to report Whittaker’s crimes," they added.
"We apologise unreservedly to him for the appalling abuse he suffered."
Sussex Police Det Con Nicky Beard said: "Ifor Whittaker is a predator who used his position of trust in the community to rape and sexually abuse young children.
"That level of betrayal must not be underestimated.
"The effects of that abuse have lasted a lifetime, but he has shown incredible strength and courage to report Whittaker’s crimes to police and ensure he has faced justice."