2023 European Athletics U23 Championships – Men's 400 metres hurdles

The men's 400 metres hurdles event at the 2023 European Athletics U23 Championships was held in Espoo, Finland, at Leppävaara Stadium on 14 and 15 July.

Records
Prior to the competition, the records were as follows:

Round 1
Qualification rule: First 3 in each heat (Q) and the next 4 fastest (q) advance to the Semi-Finals.

Semifinals
Qualification rule: First 3 in each heat (Q) and the next 2 fastest (q) advance to the Final.

Final
Wind: +0.5 m/s