UEFA Euro 2020 was an international football tournament held across eleven cities in Europe from 11 June to 11 July 2021. The 24 national teams involved in the tournament were required to register a squad of up to 26 players – of which three had to be goalkeepers – by 1 June 2021, 23:59 CEST (UTC+2),^[1] ten days prior to the opening match of the tournament.^[2] Only players in these squads were eligible to take part in the tournament.

In the event that a player on the submitted squad list suffered from an injury or illness prior to his team's first match of the tournament, that player could be replaced, provided that the team doctor and a doctor from the UEFA Medical Committee both confirmed that the injury or illness was severe enough to prevent the player from participating in the tournament.^[3] Should a goalkeeper have suffered from an injury or illness after his team's first match of the tournament, he could still be replaced, even if the other goalkeepers from the squad were still available. A player who had been replaced on the player list could not be readmitted to the list.^[4]

The position listed for each player is per the official squad lists published by UEFA. The age listed for each player is their age as of 11 June 2021, the first day of the tournament. The numbers of caps and goals listed for each player do not include any matches played after the start of the tournament. The club listed is the club for which the player last played a competitive match prior to the tournament. The nationality for each club reflects the national association (not the league) to which the club is affiliated. A flag is included for coaches who are of a different nationality to their team.

At the start of April 2021, UEFA stated they were considering allowing tournament squads to be expanded from the usual 23 players, used at every European Championship since 2004, following calls from national team managers in case of a possible COVID-19 outbreak in a team, as well as to reduce player fatigue caused by the fixture congestion of the prior season.^[5] On 27 April, it was reported that the UEFA National Team Competitions Committee had approved the expansion of squads to 26 players, subject to confirmation by the UEFA Executive Committee.^[6]

On 4 May 2021, the Executive Committee confirmed the use of 26-player squads. However, teams still could only name a maximum of 23 players on the match sheet for each tournament fixture (of which 12 were substitutes), in line with the Laws of the Game.^[4]

Players who either tested positive for SARS-CoV-2 or had been declared as "close contacts" of a positive SARS-CoV-2 tested person – and therefore were put in isolation by the decision of health authorities – were considered cases of serious illness and could therefore be replaced before the first match.^[4]

If a group of players of a team were placed into mandatory quarantine or self-isolation prior to a match following a decision from national or local health officials due to positive SARS-CoV-2 tests, and fewer than 13 players were available (including at least one goalkeeper), additional players could have been called up to meet the minimum of 13 players required. In such a case, an equivalent number of quarantined players must have been definitively withdrawn from the 26-player list.^[7]

Any player who had been replaced on the player list after the submission deadline of 1 June 2021 could not be readmitted to the list.^[4]