Michael Leshner and Michael Stark wed Tuesday in a civil ceremony observed by Leshner's 90-year-old mother and about 50 friends and observers.
"We're blissfully happy," said Leshner, a Toronto lawyer, after exchanging rings with his partner of 22 years and offering a champagne toast outside the courthouse.
An Ontario appeals panel on Tuesday declared the legal definition of marriage invalid and ordered Toronto's city clerk to issue marriage licenses to the homosexual couples involved in the case.
The Ontario attorney general said Wednesday the province would respect the court ruling, meaning the marriage that followed would get registered.
"I'm charged to follow the laws and will follow the laws with regards to this matter," Norm Sterling said. "We said during the appeal process that the province of Ontario would follow the court ruling."
Canadian law now defines marriage as a union between a man and a woman. Tuesday's ruling changed it in Ontario to a union between two people.
It was the latest in a series of court rulings against a federal ban on same-sex marriage, increasing pressure on Prime Minister Jean Chretien's government to change the law or let the ruling stand.
The government can appeal Tuesday's decision to Canada's Supreme Court, an option Chretien said the government would have to study further before deciding.
Leshner said it would be impossible for Canada to return to the limited definition of marriage regardless of whether the government appeals.
"The argument's over," he said. "No more political discussion, we've won. It's a great day for Canada."
Conservative political parties called on the government to appeal, and Alberta Premier Ralph Klein said he would fight any effort to force his province to allow same-sex marriages.
Gay rights advocates urged the government to accept the decision.
"Stop the appeals, stop the obstruction, stop the waste of taxpayers dollars in fighting inequality," said Svend Robinson, a homosexual lawmaker for the New Democratic Party who has pushed for expanding the marriage definition.
"I really can't believe that we've reached this day," Robinson said. "For the first time in our country's history, gay and lesbian people are actually marrying."
A Parliament committee is studying the matter, and opinion polls indicate a slight majority of Canadians favor legalizing same-sex marriages nationwide. Heritage Minister Sheila Copps said Tuesday it was time to change the marriage definition to reflect modern social mores.
"When you're speaking about equality, you're talking about allowing people to exercise all rights under the law including all rights that are available to all others," Copps said.
Tuesday's Ontario ruling upheld a lower court decision.
Last month, a British Columbia appeals court also ruled the federal government should change the law.
The court set a deadline of July 12, 2004, saying that otherwise, it would rewrite the legal definition of marriage to read "the lawful union of two persons to the exclusion of all others."
A Quebec court also has ruled against the federal ban. Quebec recognizes homosexual civil unions, which are separate from formal marriage.
In the United States, homosexual marriage lacks full legal recognition in all 50 states, said Evan Wolfson, executive director of Freedom to Marry, a New York-based group promoting support for the issue among heterosexuals.
Vermont recognizes civil unions that give homosexual couples the full benefits and responsibilities of marriage, but are separate from legal marriage.
Wolfson said legal challenges in several U.S. states, including Hawaii, Massachusetts, New Jersey and Indiana, show the issue is gaining prominence.