The bill will now proceed to the Lower House next week for one final vote, before same-sex marriage is expected to pass into Australian law.
The Dean Smith bill will next week proceed to the House of Representatives, where the majority of MPs will need to vote in favour before the Marriage Act is finally changed.
Prime Minister Malcolm Turnbull has promised to legalise same-sex marriage by Christmas and recently announced the House of Representatives would not break for the holidays until the law is passed.
Supporters of the law hailed a “historic event”, while one prominent No campaigner – Senator Barry O’Sullivan – congratulated supporters of the change for their success.
Only 12 senators voted No on the bill, although a number of senators including One Nation leader Pauline Hanson abstained from the vote instead. The No voters included a number of Coalition conservatives - including senators Canavan, Fierravanti-Wells and Eric Abetz - as well as Labor senators Chris Ketter and Helen Polley.
The Liberal senator who sponsored the bill, Senator Dean Smith, said the bill was the “fulfillment” of the wishes of the Australian people, who voted ‘Yes’ by a 61.6 per cent margin in a national postal survey earlier in the month.