Fr Michael Moloney left the priesthood almost four decades ago to get married and start a family.
Fr Moloney, who is originally from Tipperary and who is a curate in Daingean in Co Offaly, applied to rejoin the priesthood when his wife Marjorie died in 2005.
He conducted the marriage ceremony for his second son Paul and partner Deborah Coyle at the Garrison Church adjacent to Renmore barracks in Galway.
Fr Moloney's two grandchildren, Abbie (7), and Cian (6), were among 200 guests at the wedding, with a reception afterwards in the Salthill Hotel.
Fr Moloney said that it was heartening that the church had been able to cope with his return.
"I have been able to experience life from all aspects and I am delighted to be able to perform this ceremony," said Fr Moloney, who paid tribute to Bishop Jim Moriarty for readmitting him to the priesthood.
Fr Moloney said he still considered himself a married man, five years on from his wife's death.
The groom admitted it was unusual for a dad to perform the marriage ceremony.
"But with all that is going on in the church it is very reassuring to have someone like him as a priest. He has been through life," said Paul.
Fr Moloney, who is in his late sixties, was originally ordained in December 1966.
He served as a missionary in Egypt and at Ballinafad College in Co Mayo.
But he asked to be laicised in 1969 and three years later his laicisation was granted by the Catholic Church.
He married an Irish woman who he had met in Zambia and Michael and Marjorie Moloney had three sons and one daughter.
In May 2006 -- 37 years after leaving the priesthood -- he applied to the Pope for his laicisation to be rescinded and to be readmitted to the exercise of the priestly ministry.
SIC: II