Mixed is an ethnicity category that has been used by the United Kingdom's Office for National Statistics since the 1991 Census. Colloquially it refers to British citizens or residents whose parents are of two or more different races or ethnic backgrounds. Mixed-race people are the fastest growing ethnic group in the UK and numbered approximately 1 million in 2009.

In the 2001 census, 677,177 classified themselves as of mixed race, making up 1.2 per cent of the UK population.Office for National Statistics estimates suggest that 956,700 mixed race people were resident in England (as opposed to the whole of the UK) as of mid-2009, compared to 654,000 at mid-2001. As of May 2011, this figure surpassed 1 million. It has been estimated that, by 2020, 1.24 million people in the UK will be of mixed race.. Research conducted by the BBC, however, suggests that the mixed race population could already be twice the official estimate figure - up to 2 million..

3.5 per cent of all births in England and Wales in 2005 were mixed race babies, with 0.9 per cent being Mixed White and Black Caribbean, 0.5 per cent White and Black African, 0.8 per cent White and Asian, and 1.3 per cent any other mixed background.