Mr Herbert says the Tories could have 15 openly gay MPs after the election
Tory frontbencher Nick Herbert says there has been a "self-evident" change in his party's attitude to gay people.
In a speech in the US, the shadow environment secretary promised action on homophobic bullying and hate crimes, with new laws if necessary.
Mr Herbert, who is gay, argued the Tories once "drove away" millions of potential voters, but were now part of the consensus for "progress".
But Labour dismissed his comments as a "PR exercise".
Conservative leader David Cameron has apologised for Section 28 - the controversial law brought in by his party in 1988 banning local authorities from portraying homosexuality in a positive light.
'Clear pink water'
Mr Herbert gave a speech at the Cato Institute in Washington DC on the theme "Is there a place for gay people in conservatism and conservative politics?"
He said: "Conservatives should always believe that everyone should have an equal chance in life, regardless of any other factors, and that they should not be discriminated against."
He added: "In the UK, all three major political parties are now assuring gay people that it's safe to vote for them.
"Typically, far from taking pleasure in this new consensus, the Left has greeted it with dismay.
"For over a decade they have sought to build a client state, where groups are beholden to their generosity. And now they want to open up 'clear pink water' between themselves and the Conservative Party...
"But we self-evidently have changed... The truth is that there are millions of people who we drove away but who share our values and want to join us."
Mr Herbert said that, if the Tories won a majority at the next general election they would have at least 15 openly gay MPs - which, he argued, was likely to be more than Labour.
He said: "If we form the next government, we intend to entrench the progress made on gay equality, and to move the agenda forward.
"If there is a need for new laws, we will consider them."
Mr Herbert, who represents Arundel and South Downs, said: "We will take the strongest stand against the homophobic bullying of children in schools, as we should take a stand against all bullying - and we will not allow our support for faith schools to undermine that stand.
"We will insist on action against hate crime where gay people are the victims, as we should insist on action against all hate crime which incites fear and violence.
"We will speak out when countries abuse the human rights of gay people, as we should speak out when any human rights are abused."
Culture Secretary Ben Bradshaw, who is one of Labour's openly gay MPs, said: "The Tories need to be honest before they can claim to have really changed.
"Only last week David Cameron was air-brushing his own record on equality denying he had opposed adoption by same sex couples when in fact he voted against it.
"Most people will see through this PR exercise, remembering the progress made under Labour was opposed at every turn by Conservative MPs and peers, including very recently important measures in the Equality Bill."