Nations have been able to pick 26-man squads at the most recent World Cup and Euros tournaments
The European governing body's executive committee confirmed the increase from 23 players on Friday after the national competitions committee voted in favour of the change in April.
Teams were allowed 26-man squads at Euro 2020 due to the impact of Covid-19 but Uefa had initially planned to revert to 23-strong groups at Euro 2024.
Expanded squads were also permitted at the 2022 World Cup in Qatar because it was played in the middle of the domestic season.
Participating teams do not have to name an extended squad but must submit a list of at least 23 players to Uefa by 7 June.
The news will be welcomed by several international managers who were critical of the idea of reducing squad sizes for the tournament, with Netherlands boss Ronald Koeman calling it "absurd", external.
England manager Gareth Southgate had previously been in favour of 23-man squads but the number of injuries being suffered across the Premier League this season altered his thinking.
He will name his squad on 21 May, two days after the end of the Premier League season.
Euro 2024 begins on 14 June with Scotland taking on hosts Germany in the first game, while England's campaign gets under way on 16 June when they face Serbia.
-- Courtesy of BBC Sport