Britain left EuroHPC as a result of leaving the European Union at the start of 2021 but is becoming a member as part of rejoining the Horizon Europe science programme last year.
EU states as well as countries including Norway and Turkey are part of the scheme.
Joining the programme does not involve extra taxpayer money up front, but if British researchers or businesses receive grants from the programme to access supercomputing resources, funding is matched by the Government.
Saqib Bhatti, the digital economy minister, said joining the scheme was “an example of collaborating where we think it is beneficial for us to do so”.
In March, the UK also joined the EU’s semiconductor research programme, designed to allow microchip companies to carry out advanced research.
The Government has committed £1.5bn to boosting supercomputing facilities in the UK, with AI computing hubs in Bristol and Cambridge and a new “exascale” supercomputer in Edinburgh.
Michelle Donelan, the Science, Innovation and Technology Secretary, said: “I have made it my mission to unleash the benefits of AI for the British public and supercomputers are essential tools that our best and brightest researchers need to deliver breakthroughs that will grow the economy and improve all our lives, from healthcare to energy security.”