Rugby legend Brian O'Driscoll and one of the country's most high-profile nuns, Sr Stanislaus Kennedy, have teamed up to encourage a 'Yes' vote in the marriage referendum.
O'Driscoll, a father-of-two, took to Twitter over the weekend to encourage his followers to support the move for change, saying: "I'm supporting the Yes Equality campaign for a 'Yes' vote on May 22nd".
'Sr Stan' is well known for her charity work on behalf of the homeless and immigrants over many years.
A member of the Sisters of Charity, Sr Stan said: "I have thought a lot about this. I am going to vote 'Yes' in recognition of the gay community as full members of society.
"They should have an entitlement to marry. It is a civil right and a human right."
Grainne Healy, spokesperson for Yes Equality, said Sr Stan is a much-respected public figure in Ireland and her "thoughtful reflection" on the issue is "warming and uplifting".
"She joins a line of thoughtful, committed and compassionate Catholics who have given affirmation to lesbian and gay people in Ireland, and are staunchly supporting a 'Yes' vote in the referendum," she said.
Meanwhile, Fr Pádraig Standún, parish priest of Carna in Connemara, also said that passing the referendum is "the right thing to do". He said: "It's time that gay people had the same rights as everyone else."
Meanwhile, Geoffrey Shannon, Chair of the Adoption Authority of Ireland and Special Rapporteur on Child Protection, said the birth mother will retain the right to refuse a same-sex couple from adopting her child.
"Whether people vote yes or no, the adoption process is not going to change," he said, adding that he is not advocating that people should vote one way or another.
"The birth mother's consent must be full, free, and informed. The birth mother is involved from the earliest stages in the adoption process. If the birth mother decides that she does not want to place her child with a same-sex couple, that decision will invariably be respected," he said. "The best interests of the child is the overarching consideration."