Kenny addressed the issue in a speech celebrating the 25th anniversary of the Dublin Business Innovation Center, The Irish Times reported. He said the government has decided to support the Constitutional Convention's finding that gay marriage and some other issues should be decided by popular vote.
"In respect of today's decision I support that very strongly and will campaign for it when it comes," Kenny said.
The government also plans to draft legislation allowing same-sex couples to adopt children.
Kenny's stand is likely to put him at odds with the Catholic Church. The church also campaigned against Ireland's new abortion law, which allows women to terminate pregnancies that would put their lives at risk.
"The debate at the heart of the referendum announced by the Government is not about equality," Denis Nulty, bishop of Kildare and Leighlin, said in a statement issued on behalf of the bishops. "It is about the very nature of marriage itself and the importance society places on the role of mothers and fathers in bringing up children."
But the move comes at a time when Pope Francis appears to be urging the church to reconsider its position on homosexuality.