Same-sex marriages became legal in the state on the stroke of midnight. Voters approved the change in a November referendum.
A number of couples had scheduled weddings for just after midnight, The Washington Blade reported. They included two women who tied the knot in an Annapolis church.
Baltimore City Hall opened its doors for weddings at 12:30 a.m. Among the first to get married was James Scales, a longtime aide to the mayor.
Mayor Stephanie Rawlings-Blake was present for the weddings.
"New Year's Day will have a new meaning for the hundreds -- if not thousands -- of couples who will finally have the right to marry the person they love," she said. "It is a remarkable achievement for Maryland, and we are excited to open City Hall to host some of the first wedding ceremonies in our great state."
With last year's referendums in Maryland, Maine and Washington State, gay marriage is now legal in nine states and the District of Columbia. The Maine law took effect last Saturday.