UK Biobank is a long-term prospective biobank study in the United Kingdom (UK) that houses the de-identified biological samples and health-related data of half a million people. The volunteer participants aged 40–69 were recruited between 2006 and 2010 from across Great Britain and consented both to share their health data and to be followed for at least 30 years thereafter, with the aim to enable scientific discoveries into the prevention, diagnosis, and treatment of disease.

Based in Stockport, Greater Manchester, UK Biobank is incorporated as a limited company and registered charity in England and Wales, and registered as a charity in Scotland.

UK Biobank holds more than 10,000 variables of data on many of their 500,000 participants to inform research including biological samples, physical measurements, body and brain imaging data, bone density data, activity tracking and lifestyle questionnaire data. Participants continue to provide more data over time. They have over 15 million biological samples stored, which can be requested for use by researchers, and their online database holds over 30 petabytes of data. Their human genome sequencing database, proteomic database, and human imaging project are the largest in the world. The project is enabling scientists to study the onset of diseases such as cancers, heart disease, and age-related conditions in the early stages of their development. Nature has referred to UK Biobank as an "unprecedented open access database."

Since 2012, 30,000 researchers from over 90 countries have registered to use UK Biobank. As of November 2023, there have been over 9,000 peer-reviewed publications using UK Biobank data, including over 3,000 in 2023.

UK Biobank is funded by the Medical Research Council (MRC), the Wellcome Trust, UK government and charitable sources, and philanthropic donations.

UK Biobank was conceived in the early 2000s and founded in November 2003. Professor Sir Rory Collins was appointed as the Principal Investigator and Chief Executive of UK Biobank in 2005.' An incremental approach was adopted to developing the study procedures and technology, using systems designed and developed by the Clinical Trial Service Unit (CTSU). This consisted of a series of pilot studies of increasing complexity and sophistication with interludes for assessment of results and additional scientific input. In-house trials were conducted during 2005, and a fully integrated clinic was run at Altrincham, Greater Manchester throughout Spring 2006 where 3,800 individuals were assessed. On 22 August 2006, it was announced that the main programme would recruit men and women aged between 40 and 69 based from up to 35 regional centres.

Following the initial pilot stage in the 2005–06 period, the main study began in April 2007 and by the end of that year 50,000 people had taken part. Recruitment reached 100,000 in April 2008, 200,000 in October 2008, 300,000 in May 2009, 400,000 in November 2009 and passed the 500,000 target in July 2010. The volunteers were largely healthy, wealthy and white European. Rather than recruiting more participants into the biobank, the organisation is helping other institutions establish and run similar initiatives. Participant enrolment was declared complete in August 2010. However recruitment proved more efficient than hoped and only 22 centres had been opened when the recruitment target of 500,000 was reached in 2010.

In May 2023, UKRI announced that UK Biobank was set to receive £127.6 million to move to a purpose-built facility at Bruntwood SciTech's Manchester Science Park.