The British government says that Wembley Stadium can host more than 60,000 fans for the semi-finals and final of Euro 2020.
The new levels mean the stadium will be at 75% capacity for the final three games, which come to an end with the final on July 11.
All ticket holders will need to have either a negative COVID-19 test or proof of full vaccination.
That means they must have two doses, received 14 days before the match.
The announcement came after Italian Prime Minister Mario Draghi called for the final to be moved from London to Rome, because of the rising COVID-19 cases in England.
UEFA president Aleksander Ceferin welcomed the increased capacity and thanked the UK government for the move.
UEFA has been negotiating with the UK government about relaxing quarantine restrictions on overseas fans travelling to London for games but there was no mention of any change in the statement.
Currently, COVID-19 regulations require visitors from most European countries to quarantine for 10 days after arriving in the UK.