Arlene Foster's decision to attend an LGBT event in Northern Ireland next week represents an important step towards dialogue, the organisers said.
The PinkNews reception at the seat of Northern Ireland's suspended devolved parliament at Stormont will be held on June 28.
Campaigners said it was the first time a DUP leader had agreed to take part in such an occasion.
The country is the only part of the UK where same-sex marriage is not available.
Change is strongly opposed by Democratic Unionists, who argue that civil partnerships are already available and believe marriage is between a man and a woman.
Benjamin Cohen, chief executive and editor-in-chief at PinkNews, said: "The decision by Arlene Foster to attend the first PinkNews event in Belfast is an important step towards encouraging a dialogue in Northern Ireland and we're delighted that there will be a number of other senior cross-party representatives attending and speaking."
Political powersharing has been suspended in Northern Ireland for months, with Sinn Fein raising identity and rights issues such as same-sex marriage as key matters to be addressed in negotiations.
Mrs Foster recently met members of the Fermanagh Gaelic Athletic Association (GAA) and the Muslim community as part of a series of gestures aimed towards greater inclusivity.
She said: "I intend to accept that invitation to demonstrate my acknowledgement of that contribution and to recognise the reality of diversity among our citizens.
"For me I believe I can hold to my principled position, particularly in reality to the definition of marriage, whilst respecting the diversity across our society and recognising that sexuality is a matter for the individual.
"All I ask in return is that my, and our views, are also respected and not the subject of the vilest of abuse as has sometimes been the case by a small minority."
Mrs Foster said her party was not changing its position on marriage but reaching out to acknowledge the contribution made by a section of the community.
"Just because we disagree on marriage does not mean that I can't say that we value those who are LGBT in our society and they should not be the subject of hate because of their sexuality.
"Remember, everyone is equal under the law and equally subject to the law."
She said unionism stood for pluralism and multiculturalism.
"We must be inclusive and welcome all, recognising they bring added value to a broader and greater overall sum.
"I want to genuinely reach out to our minority communities and show them the hand of friendship, recognising they have made Northern Ireland their home.
"If we truly believe in equality of opportunity for all in Northern Ireland, then we must respectfully engage and reach out to those who perhaps have not always been respectful of our position. We do so from a position of strength."
John O'Doherty, director of the Rainbow Project in Belfast which campaigns on same-sex issues, said: "While I and many in our community have been hurt by comments and actions by members of the DUP over many years, the only way we can achieve a Northern Ireland that is welcoming of all people is through dialogue, learning and of course listening."