All eight Welsh Conservative MPs opposed legalising same-sex marriage in England and Wales.
But the UK government's legislation, The Marriage (Same Sex Couples) Bill, has been overwhelmingly voted in by 400 to 175, a majority of 225.
The plans have been strongly backed by Prime Minister David Cameron but the issue has caused a Tory party split.
Most Welsh Liberal Democrats, Plaid Cymru and most Labour MPs voted in favour of the plans.
The Marriage (Same Sex Couples) Bill would enable same-sex couples to get married in both civil and religious ceremonies, where a religious institution had formally consented, in England and Wales.
It would also allow couples who had previously entered into civil partnerships to convert their relationship into a marriage.
Welsh Secretary David Jones and Wales Office minister Stephen Crabb said the vote was a conscience issue but declined to give interviews on the subject.
Two prominent local Tories, Peter Davies and Rene Kinzett, have explained their opposing views on the issue.
Another, Roy Garner, the former chairman of Monmouth Conservative Association, told BBC Radio Wales there was no appetite for a fight at grassroots level.
He said the matter would count at the ballot box.
"There comes a point as the Labour Party found in the '70s where there was a step too far and the SDP was born as a result of it.
"So Cameron's got to decide just how far he's pushing working supporters on this and frankly I think he's pushing them too far."
However, Rene Kinzett, who chairs the Tory Reform Group in Wales, said a change in the law would "recognise that couples in same sex relationships deserve the same rights and should be subject to the same responsibilities as opposite sex couples".
Plaid Pride, the lesbian, gay, bisexual, and transgender (LGBT) group for Plaid Cymru members and supporters, said it welcomed the unanimous support for the Bill from the party's Westminster MPs Jonathan Edwards, Elfyn Llwyd and Hywel Williams.
Plaid Pride co-chairman Ed Gareth Poole said: "As LGBT Plaid Cymru members and supporters, we are proud that our party has today given a ringing endorsement of equality by voting unanimously for equal marriage in the House of Commons."
'Insult to tradition'
On Sunday, more than 20 current and former constituency chairmen delivered a letter to 10 Downing Street urging the prime minister to delay any parliamentary decision on gay marriage until after the next election.
They warned of "significant damage to the Conservative Party in the run-up to the 2015 election" if the plans enter law.
Canon Andrew Knight, the vicar of Sketty in Swansea, who is opposed to gay marriage, told BBC Radio Wales that more time was needed to examine the impact of civil partnership.
"This is an insult not only to the Christian tradition of 2,000 years, but to the Muslim tradition and the Jewish tradition, and in fact the whole tradition of Western religion right the way back," said Canon Knight.
"Are we going to say that teachers must teach equivalence or are we going to wait until we can say how does civil partnership affect the physical and mental health of those involved as compared to straight couples?"
But the Reverend Andrew Morton, who last year resigned as vicar of Llangybi in Monmouthshire over the issue of gay marriage, maintained there was no reason for further delays.
"Certainly my issue with the church at large is that... in many respects it is misogynistic and homophobic - and I think the debate has been going on for a long time," he said.
"We have got to finally sort it out as a Christian institution."