The Belgium national under-21 football team is the national under-21 football team of Belgium and is controlled by the Belgian Football Association. The team competes in the European Under-21 Football Championship, held every two years. Their biggest successes were winning the 2007–09 International Challenge Trophy and reaching the European Championship semi-finals in 2007 in the Netherlands. Thanks to the latter achievement, Belgium qualified for the football tournament at the 2008 Summer Olympics. Their current home stadium is Den Dreef in Leuven.

Belgická fotbalová reprezentace do 21 let (francouzsky: Équipe de Belgique espoirs) představuje Belgii na mezinárodních fotbalových turnajích v kategorii U21 a na olympijských hrách. Od roku 1976 ji řídí Královská belgická fotbalová asociace.