Around 3% of people in England and Wales aged 16 or over identify as lesbian, gay or bisexual, according to 2021 census data released on Friday.
The census in 2021 was the first in Britain to ask about people's sexual orientation, and the results are broadly in line with previous, smaller-scale surveys.
The census, conducted by Britain's Office for National Statistics (ONS), also asked about people's gender identity for the first time. About 262,000 people - 0.5% of those aged 16 or over - replied that the gender they identified with was different from their sex registered at birth, the ONS said.
The questions about sexual orientation and gender identity were voluntary, and 7.5% of people declined to answer about their sexual orientation, while 6.0% did not answer the question on gender identity.
Overall, 43.4 million people in England and Wales said they were "straight or heterosexual", while 1.5 million - 3.2% of the population aged 16 or over - identified as gay or lesbian, bisexual, or other.
Some 1.5% of people said they were gay or lesbian and 1.3% were bisexual. Another 0.3% ticked a box for "other sexual orientation", two thirds of whom called themselves pansexual.
On gender identity, 262,000 people aged 16 or over answered that they were a different gender to the sex they were registered as at birth, the ONS said.
Of those, 48,000 said they now identified as a trans man, 48,000 identified as a trans woman, 30,000 said they were non-binary and 18,000 said they had another gender identity, the ONS added.
The ONS defines a trans man as someone who identifies as a man but was registered female at birth, while trans women were registered as male at birth, but now identify as women.
Census figures for Britain as a whole are not yet available, as Scotland delayed carrying out its census for a year due to the COVID
A previous, annual UK-wide survey conducted by the ONS showed that in 2020 3.8% of people identified as gay or lesbian, bisexual or other, up from 1.9% in 2014 when same-sex marriage was first allowed in England and Wales.
That survey also gave breakdowns of sexual orientation by age, gender and ethnicity - showing, among other things, that younger people are much more likely to identify as lesbian, gay or bisexual.
Sex between men aged 21 or over was legalised in England and Wales in 1967. The age of consent was lowered to 18 in 1994 and reduced to 16 - the same as for heterosexual relationships - in 2000.
Census data on sexual orientation by age will be published on Jan. 25, and further details will come later in the year.