2023 European Athletics U23 Championships – Men's 400 metres

The Men's 400 metres event at the 2023 European Athletics U23 Championships was held in Espoo, Finland, at Leppävaara Stadium on 13 and 14 July.

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

Heats
Qualification rules: First 3 in each heat (Q) and the next 4 fastest (q) will qualify for the semi-finals.

Semi-final
Qualification rules: First 3 in each heat (Q) and the next 2 fastest (q) will qualify for the semi-finals.