The men's 400 metres hurdles at the 2022 World Athletics U20 Championships was held at the Estadio Olímpico Pascual Guerrero in Cali, Colombia on 3, 4 and 5 August 2022.

[1] U20 standing records prior to the 2022 World Athletics U20 Championships were as follows:[2] Qualification: First 3 of each heat (Q) and the 3 fastest times (q) qualified for the semifinals.

[3] Qualification: First 2 of each heat (Q) and the 2 fastest times (q) qualified for the final.

[4] The final was held on 5 August at 17:49.

[5]