The plaintiffs come from communities across the state, according to a gay-rights activist familiar with the lawsuit. He would not provide other details.
New Jersey recognizes civil unions by gays and lesbians, but lawmakers voted down a marriage bill in January 2010.
Last week, State Sen. President Stephen Sweeney (D., Gloucester) said his vote was the "biggest mistake of my legislative career."
"I made a decision purely based on political calculation to not vote for marriage equality," Sweeney said. "I failed in my responsibility as majority leader to actually lead. I was wrong."
After the vote, the state Supreme Court declined to hear a case for gay marriage until the issue came before lower courts.
Another bill seeking legalization of same-sex unions is before the Assembly, but gay-rights groups have said they do not think the measure has enough votes to survive a Christie veto.
"It's not something I support," Christie said Sunday on NBC's Meet the Press. "I believe marriage should be between one man and one woman.
"That's my view," he said. "And that will be the view of our state, because I wouldn't sign a bill . . . like the one that was in New York."
On Friday, New York became the sixth and most populous state to legalize same-sex marriage. The law will take effect on July 24.
Massachusetts was first to allow the unions, under court order, in 2004. New Hampshire, Connecticut, Iowa, and Vermont, as well as the District of Columbia, also have legalized same-sex marriage.
Contact staff writer Edward Colimore at 856-779-3833 or firstname.lastname@example.org.