Other countries include Denmark, Iceland, Norway, Sweden, Portugal, Spain, Belgium, France and the Netherlands.
It was also made legal in England, Wales and Scotland in 2014.
British singer Elton John has today married long-time partner David Furnish near London – taking advantage of new gay marriage laws.
John, 67, toasted his special day with online followers using the hashtag #sharethelove
Couples who are already in a civil partnership in England and Wales have been able to convert their commitment into marriage since December 10.
Same-sex marriage has been legal in both countries since March 13, 2014.
The marriage took place in Windsor, nine years to the day since the pair’s civil union.
“I’m very proud of Britain and the laws that we’ve seen come into existence since we’ve been together,” John told US network NBC in March.
“Having our civil partnership was an incredible breakthrough for people that have campaigned for a long time — through the ’60s and the ’50s in England when it was so hard to be gay and hard to be open about it. And it was a criminal act.
“So for this legislation (gay marriage) to come through is joyous, and we should celebrate it. We shouldn’t just say, ‘Oh, well we have a civil partnership. We’re not going to bother to get married.’ We will get married,” he said.