All three of Wandsworth's MPs voted in favour of same-sex marriage in the House of Commons last night.
Putney's Justine Greening, Tooting's Sadiq Khan and Battersea's Jane Ellison backed the bill which will now receive more detailed parliamentary scrutiny.
MPs voted in favour of the Marriage (Same-Sex Couples) Bill by 400 to 175, resulting in a majority of 225.
If it becomes law, the bill will enable same-sex couples to get married in religious and civil ceremonies, although the former will only be allowed with the consent of religious institutions.
Ms Ellison explained that MPs were free from pressure from party whips.
He said: "Votes on the Bill were free votes for Conservative MPs, who will not be whipped to vote one way or another.
"This means that they voted according to their individual conscience and judgement – I voted with mine in favour of equal marriage.
"Just as I support the right of same-sex couples to get married, I firmly believe that religious organisations should continue to be able to make their own decisions on this issue."
Mr Khan said his background as a human rights lawyer influenced his decision.
He said: "I voted in favour of the legislation because I believe it is fundamentally an issue of equality.
"Freedom of religion is also extremely important and it is important that faith groups should be protected.
"Freedom of religion is therefore rightly written onto the face of the legislation, meaning that no Church, Mosque or faith group will be obliged to hold same sex marriage ceremonies if they do not wish to."
Putney's Ms Greening was unavailable for comment.
Among the three major political parties, there was really only division in the Tory party.
Voting records show 136 Conservative MPs opposed the bill and 127 voted in favour - a further 35 did not vote while five abstained.
In the Labour party 217 MPs voted for same-sex marriage with just 22 opposing.
While 44 Liberal Democrats backed the bill and just four vote against it.
Prime Minister David Cameron said Tuesday's vote had been "an important step forward" while Labour leader Ed Miliband called it a "proud day".
Deputy Prime Minister and Liberal Democrat leader Nick Clegg, who is also a Putney resident, said the vote was a "landmark for equality in Britain".