The men's 400 metres at the 2018 European Athletics Championships took place at the Olympic Stadium on 7, 8, and 10 August.

[1] All times are local times (UTC+2) First 3 in each heat (Q) and the next fastest 3 (q) advanced to the Semifinals.

[2] First 2 (Q) and next 2 fastest (q) qualify for the final.

[3] *Athletes who received a bye to the semifinals[4] [5]