The Ataturk Stadium in Turkey was supposed to host the showpiece event between Manchester City and Chelsea on May 29 but the United Kingdom placed the country on its Covid-19 red list, meaning travelers would have to quarantine for 10 days on their return.
6,000 from each club will be allowed to travel to Portugal, which also hosted the latter stages of the Champions League last season, with Bayern Munich emerging victors over Paris Saint Germain in the final.
UEFA has said in an official statement, with various stadiums in England initially offered up as alternate venues: "UEFA discussed moving the match to England but, despite exhaustive efforts on the part of the Football Association and the authorities, it was not possible to achieve the necessary exemptions from UK quarantine arrangements.
"The Portuguese authorities and the FPF stepped in and worked quickly and seamlessly with UEFA to offer a fitting venue for the final and, as Portugal is a green list destination for England, fans and players attending the final will not have to quarantine on their return home.
"The decision does not come without big regret for the work that the Turkish football authorities have done over the last two years to ensure the successful staging of the final in Istanbul. UEFA is grateful also for their continued partnership and cooperative spirit as well as the understanding they showed in this particular circumstance and will urgently look into future opportunities for the city of Istanbul.
"The stadium capacity for the match will be finalised and confirmed in due course in cooperation with the Portuguese authorities and the FPF. However, fans of the competing teams will be able to buy tickets through the clubs in the usual way, with the 6,000 tickets per club going on sale as soon as possible from today. Arrangements for the sale of tickets to the general public will start on 24 May 2021 at 1400 CEST."