The Croatia national under-21 football team represents Croatia in international football matches for players 21 or under. It is governed by the Croatian Football Federation, the governing body for football in Croatia. It is a member of UEFA in Europe and FIFA in global competitions. The team's colours reference two national symbols: the Croatian checkerboard and the country's tricolour. They are colloquially referred to as the Mladi vatreni ('Young Blazers'). So far, the Mladi vatreni qualified for five UEFA European Under-21 Championships, namely in 2000, 2004, 2019, 2021 and 2023. Croatia was unable to pass the group stage until the 2021 Euro when it was eliminated in the quarter-finals, its greatest accomplishment in the European competition so far.

Horvaatia U21 jalgpallikoondis on horvaatia jalgpallikoondis, mis esindab Horvaatiat alla 21-aastaste rahvusvahelistel jalgpallivõistlustel.