[1] Vietnam are the defending champions, having won the 2022 edition[2][3] and successfully defended their title through a 6–5 victory on penalties following a 0–0 draw after extra time over Indonesia in the final, thus becoming the first team to win the tournament for a second time.

Singapore withdrew due to the country's under-23 team being subject to evaluation following the 2023 SEA Games.

[5] The following teams, all from member associations of the AFF, entered the tournament:[1] The draw for the 2023 AFF U-23 Championship was held on 29 May 2023 in Bangkok, Thailand and was streamed online in the competition's official YouTube channel.

A final squad of 23 players (three of whom must be goalkeepers) must be registered one day before the first match of the tournament.

In the knockout stage, the penalty shoot-out was used to decide the winner if necessary.