The LGB Alliance is a UK registered charity founded in October 2019 by lesbians Bev Jackson and Kate Harris in response to the redefinition of homosexuality by major LGBTQ+ organizations including Stonewall. The Alliance holds that lesbian, gay and bisexual rights are grounded in same-sex attraction — attraction to people of the same biological sex — and that replacing sex with gender identity in the definition of sexual orientation erodes the legal protections and community spaces that LGB people depend on.

The LGB Alliance has been a significant legal actor in the UK debate over sex and gender identity. It made a joint submission to the UK Supreme Court in For Women Scotland Ltd v The Scottish Ministers, the April 2025 ruling that confirmed "woman" and "sex" in the Equality Act 2010 refer to biological sex. The organization campaigned successfully against Scottish gender recognition reform legislation and has submitted more than forty policy responses to government consultations on legislation affecting LGB people.

Professor Robert Wintemute — Calgary-born Professor of Human Rights Law at King's College London and one of the original authors of the Yogyakarta Principles — serves as a trustee of the LGB Alliance. His presence on the board reflects the organization's grounding in serious human rights law scholarship, and his public revision of the Yogyakarta Principles has been an important contribution to the global debate over how LGB and transgender rights frameworks interact.