Lawmakers approved a bill Friday night, making New York the sixth, and most populous, state to legalize same-sex marriage.
Gay-marriage backers hope the vote will help politicians nationwide, including President Barack Obama, that support of gay marriage is now a mainstream viewpoint and a winning political stance.
Fred Sainz of the Human Rights campaign says New York's law "sends the message that marriage equality across the country is a question of `when,' not 'if."'
Action by Congress or the Supreme Court will likely be needed if same-sex marriage is to be recognized nationally.
Obama endorses civil unions but not gay marriage. The president has said his views on the issue are evolving and that decisions on marriage should be left to the states.
Same-sex couples can begin marrying begin 30 days after Cuomo signs the bill.
The Associated Press contributed to this report.