Queen Elizabeth II has signed same-sex marriage into law in England and Wales.
By summer 2014, the first gay couples in the UK will be able to unite in matrimony.
It is the last step in the long battle to get the Marriage (Same Sex Couples) Bill through parliament, making it an Act.
Speaker John Bercow announced the bill had received Royal Assent, and it was greeted with cheers in the House of Commons.
Equalities Minister Maria Miller said: 'The fact that the Bill passed through both Houses undefeated is a huge accomplishment for the Government.
'This is a historic moment that will resonate in many people’s lives. I am proud that we have made it happen, and I look forward to the first same sex wedding by next summer.'
The bill saw angry exchanges in both chambers of parliament but it was passed by landslide votes in the Commons and Lords. It was also backed by the leaders of all three major political parties.
Separate legislation has been presented to the Scottish Parliament to make same-sex marriage equality legal there. Debates are expected to start in October or November.
England and Wales are the 16th and 17th countries in the world to fully recognize same-sex marriage.