MPs have voted to force the Government to liberalise access to abortion and allow same-sex marriage in Northern Ireland if devolution is not restored.
Gay marriage is illegal in Northern Ireland, while terminations are only allowed in cases where a woman's life is at risk or if there is a danger of permanent and serious damage to her mental or physical health.
The votes were held as part of House of Commons measures aimed at keeping Northern Ireland public services running, two and a half years after devolved powersharing collapsed.
Campaigner John O'Doherty said: "Our future got a little brighter today and we hope that LGBT people across Northern Ireland will wake up tomorrow feeling more hopeful for the future we all want to see."
MPs voted by a majority of 310, 383 to 73, to legalise same sex marriage if a new Stormont Executive is not formed by October.
A proposal aiming to extend abortion access was also approved – 332 votes to 99.
The issues are areas of significant dispute between the DUP and Sinn Fein, who have struggled for years to reconcile their differences and resurrect the institutions at Stormont.
Director of The Rainbow Project and member of the Love Equality civic campaign Mr O'Doherty said: "Parliament has always had the power to legislate for marriage equality in Northern Ireland and we are glad the House of Commons has seen sense and voted to give people in Northern Ireland the same freedoms enjoyed by everyone else in these islands.
"All love is equal and we are proud to celebrate this achievement with our community, friends, colleagues and allies from across these islands."
The DUP and religious leaders believe marriage is between a man and woman and civil partnerships are an option for same-sex couples.
Sinn Fein and a coalition of civic society activists believe the change is an issue of equality and human rights.
Minister for Women and Equalities, Penny Mordaunt, said: "Proud to have supported this amendment. Every citizen of the UK should be able to marry who they love.
"The fact that people in Northern Ireland have been unable to has torn at the social fabric of our country."
Access to abortion is also a major touchstone issue in Northern Ireland, with large numbers of women travelling to Great Britain for terminations, and mass rallies for and against medical provision at home.
Ann Furedi, chief executive of the British Pregnancy Advisory Service, said: "We are extremely grateful to all those MPs from across the UK who made clear that they would no longer turn a blind eye to the injustice and suffering faced by the women of Northern Ireland.
"The Government has been told repeatedly by the Supreme Court, the United Nations Committee against Torture, and the UN Committee for the Elimination of All Forms of Discrimination Against Women that the current law – which forces women to travel to England for the healthcare they need or risk prosecution and punishment by using pills bought online – breaches women's human rights."