Billionaire Albert Gubay was said to be "overwhelmed" as he was presented with a Papal award.
In a 30-minute ceremony at St Anthony's Church in Onchan, 82-year-old Mr Gubay was given a Papal Knighthood.
The award was in recognition of the businessman's decision to give away half of his fortune to the church.
Archbishop of Westminster, Vincent Nichols, said: "I think it would be true to say that Mr Gubay feels overwhelmed."
"He is not a man who seeks publicity," he added.
"I only know of one other person in the British Isles, who is not a Catholic, who has the same award. This is very rare but Mr Gubay's generosity is also very rare."
Speaking to the BBC ahead of the ceremony, Mr Gubay, the founder of the Kwik Save chain, said his success was down to hard work, a lot of luck - and a "partner" he first found help from when aged in his 20s and penniless with two young children.
The Knight Commander with Star of the Order of St Gregory the Great, an order bestowed by the Pope which dates back to 1831, is given for conspicuous service to the Church and society.