The Wales national under-21 football team, also known as the Wales U21s, is the national under-21 football team of Wales and is controlled by the Football Association of Wales. The team competes in the UEFA European Under-21 Football Championship, held every two years. To date Wales haven't yet qualified for the finals tournament but in recent years have shown good form, losing in a playoff (5–4) to England in the 2009 qualifying campaign and finishing second in their group two years later, after leading their group until their last game Wales only needed a draw to qualify for the play-offs but lost 1–0 away to Italy.

The under-21 team came into existence following the realignment of UEFA's youth competitions in 1976. A goalless draw in a friendly against England at Wolverhampton Wanderers' Molineux Stadium was Wales U21s' first result.

The national under-21 team is the highest level of youth football in Wales, and is open to any players who were born in Wales or whose parents or grandparents were born in Wales. This team is for Welsh players aged 21 or under at the start of a two-year European Under-21 Football Championship campaign, so players can be, and often are, up to 23 years old. Also in existence are teams for Under-20s (for non-UEFA tournaments), Under-19s and Under 17s. As long as they are eligible, players can play at any level, making it possible to play for the U21s, senior side and again for the U21s.

Velšský fotbalový tým do 21 let představuje Wales na mezinárodní úrovni v mládežnických soutěžích a přátelských zápasech. Tým řídí FAW a v současné době jej vede kouč Paul Bodin.

Wales U21 neměl dosud takový úspěch jako seniorský tým, přesto se účastnil několika velkých turnajů. V roce 2017 se kvalifikovali na mistrovství Evropy UEFA do 21 let, jejichž hostitelem bylo Polsko. V roce 2019 se také kvalifikovali na mistrovství Evropy UEFA do 21 let, jejichž hostitelem byla Itálie.

Někteří z nejlepších hráčů, kteří hráli za Wales U21, jsou Gareth Bale, Joe Allen a Aaron Ramsey. Gareth Bale je považován za jednoho z nejlepších hráčů současnosti a je držitelem mnoha ocenění, včetně ceny FIFA pro nejlepšího hráče roku 2013. Aaron Ramsey je také uznávaným hráčem, který v současnosti hraje za Juventus v Itálii.