A bill to allow same-sex marriage in England and Wales is now law, though the unions aren't expected to take place until 2014.
Queen Elizabeth II has given her assent to the bill, which the British House of Commons passed on Tuesday, the house's speaker, John Bercow, said Wednesday.
The monarch's assent -- a formality in the United Kingdom -- makes the measure official. The first same-sex wedding could be held as early as next summer.
The bill had the support of Prime Minister David Cameron, but his commitment put him at odds with many in his Conservative Party and its grass-roots supporters. The Conservatives govern in coalition with the Liberal Democrats.
The issue of same-sex marriage has also divided other nations.
A law that allows same-sex couples to marry and adopt was passed by France this year, despite large street protests and vocal opposition from religious groups.
In the United States, two landmark rulings by the Supreme Court last month gave the gay and lesbian rights movement huge political and legal momentum.
The justices said legally married same-sex couples will now enjoy the same federal benefits as heterosexual couples, striking down a key provision in the Defense of Marriage Act.
And although not granting a sweeping right of gays and lesbians to marry nationwide, a separate high court ruling effectively allows same-sex marriage to resume in California, the nation's most populous state.