This season's Champions League and Europa League competitions will be completed in August with 'final eight' tournaments in Portugal and Germany.
The Women's Champions League will take place in northern Spain.
Uefa competitions were suspended in March because of the coronavirus pandemic.
The quarterfinals and semifinals will be staged over one leg, instead of the usual two, with the final to be held on August 23, Uefa deputy general secretary Giorgio Marchetti said after an executive committee meeting held by video conference.
The four last-16, second leg matches which still have to be played – Manchester City v Real Madrid, Bayern Munich v Chelsea, Juventus v Olympique Lyonnais and Barcelona v Napoli – will take place on August 7/8, either at the originally scheduled venues or in Portugal.
Paris St Germain, Atletico Madrid, Atalanta and RB Leipzig have already qualified for the quarterfinals.
The plan allows for a quicker completion of the season than the traditional two-legged home and away format but does mean the competition will have six fewer games which will cost Uefa broadcast revenue.
Istanbul, which was due to host the 2020 final, will now instead be the venue for the 2021 edition, with all other scheduled hosts moving back a year, Uefa said.
A similar format will be used to decide the Europa League competition at German venues from August 10 to August 21.