The Sexual Offences (Amendment) Act 2000 repealed all criminal provisions regarding homosexuality; setting an equal age of consent for sexual activity between men.

On 2 November 2015, the Northern Ireland Assembly voted 53–52 in favour of same-sex marriage. However, the Democratic Unionist Party (DUP) tabled a "petition of concern", signed by 32 members, and prevented the motion from coming into effect.

Following a scandal, deputy First Minister Martin McGuinness resigned in protest on 9 January 2017 and his party, Sinn Féin, refused to nominate a successor, triggering a snap election.

In the 2017 Northern Ireland Assembly election, the DUP lost 10 of their seats in the Assembly and thus their ability to use the petition of concern mechanism. However, no party reached a large-enough majority to form a government and thus no singular government could be formed. Sinn Féin also refused to return to a power-sharing agreement with the DUP.

The Northern Ireland Assembly missed its three week deadline to establish a new Executive, which led to then-Secretary of State for Northern Ireland, James Brokenshire, giving them an extension.

After several missed deadlines, the Northern Ireland (Executive Formation etc) Act 2019 was passed and given royal assent by Queen Elizabeth II on 24 July 2019. It extended the deadline for forming a government to 13 January 2020, and required then-Secretary of State for Northern Ireland, Julian Smith, to pass new laws to legalise same-sex marriage.

These new laws came into effect on 13 January 2020, officially bringing Northern Ireland in line with England, Scotland and Wales. Since 13 January 2020, same-sex marriage has officially been legal in the entire United Kingdom.

Previous law repealed by section 122 of the Local Government Act 2003.

Per the Gender Recognition Act 2004 (in effect 2005) in all four constituent countries of the UK. The requirements are as follows:
1. Must be 18 years of age
2. Must have a gender-dysphoria diagnosis
3. Must intend "to continue to live in the acquired gender until death"
4. Has lived in the acquired gender for at least 2 years.
5. If married: must acquire the consent of the spouse.

Eligibility is determined by a Gender Recognition Panel and if approved then one is granted a gender recognition certificate and may change the gender marker on legal documents.

On May 29th 2024, the UK voted to "close the loophole" by banning private care physicians as well as prescribers registered in the European Economic Area or Switzerland from prescribing puberty blockers to children for gender incongruence. Those who already had a prescription can continue their treatment.

This measure originally was meant to last from June 3rd until September 3rd, but was extended twice and is now indefinite.

The Gender Recognition Act 2004 allows for a person to change their legal gender to either 'male' or 'female', there is no third gender option. The law came into effect on 4 April 2005.

In 2021, the UK government said (in response to a petition) that legal recognition of non-binary gender identity would have "complex practical consequences for other areas of the law, service provision and public life", and said that they felt existing legislation allowing people to change their legal gender went far enough. Courts have, however, ruled that people with non-binary identities are protected from discrimination by the Equality Act.

On 4 October 2023, then-Prime Minister Rishi Sunak asserted his stance on gender identity in a speech at the Conservative Party conference, stating it was “common sense” that “a man is a man and a woman is a woman”.

In January 2024, the High Court in London ruled that (in the case of a US citizen trying to have their non-binary identity recognised in the UK), "We have decided that whenever the Gender Recognition Act refers to ‘gender’ it refers to a binary concept – that is, to male, or to female gender. The GRP [Gender Recognition Panel] accordingly, had and has no power to issue a gender recognition certificate to the claimant which says that they are ‘non-binary’".

LGBT discrimination in the United Kingdom of Great Britain is illegal, as per the Equality Act of 2010. Sexual orientation and gender identity are covered as protected groups by the Equality Act.

Employment discrimination protections in the UK stem from several peices of legislation, which were combined into the wide-ranging Equality Act 2010. There are, however, exemptions for certain occupations (such as religious organisations).

For Local Authorities they would be bound by Equality Act 2010 and have a duty under Public Sector Equality Duty. For private landlords would be bound by Equality Act 2010

IVF treatment is available for lesbian couples too.

In the UK it is illegal to perform medical treatment onto any person without consent. For infants, consent is given by their parents on their behalf under the Children’s Act

The Ministry of Defence were forced to change their stance on when the European Court of Human Rights ruled in September 1999 that the then current ban on gays in the military was unlawful.

The 3-month deferral for MSM has been dropped in England, Wales and Scotland. Instead, donors of any gender will be asked about their recent sexual activity, and those who have only had one sexual partner within the last 3-months will be eligible to donate.
Northern Ireland is due to follow suit with these changes in September 2021.

UK law does not currently prohibit conversion therapy in any way. Conversion therapy bans have been discussed for many years. PM Boris Johnson promised to ban conversion therapy in July 2020 and this was reiterated in 2021. In March 2022, the plans were dropped, only for a partial U-turn just hours later when the government announced that the ban would go ahead but not cover trans people. On January 17 2023, the government announced they'd pass a new law to include transgender people in the conversion therapy ban.

In July of 2024, new prime minister Kier Starmer announced his government would put forward a bill to ban conversion therapy. This ban would include sexual orientation and gender identity. As of March 2025, this bill is yet to be introduced.

On November 30, 2000 a bill was signed to make the ages of consent equitable, regardless of gender. The law came into effect on August 1, 2001. The age of consent for men who have sex with men was reduced from 18 to 16, on par with different sex individuals.