| POS | Rank | Heat | BIB | ATHLETE | COUNTRY | RESULTS | ms* |
|---|---|---|---|---|---|---|---|
| 1 | 1 | 1 | 121 | Alexander DOOM |
BEL |
45.69 Q PB | |
| 2 | 1 | 2 | 313 | Karsten WARHOLM |
NOR |
45.86 Q SB | |
| 3 | 2 | 1 | 337 | João COELHO |
POR |
45.98 Q NR | |
| 4 | 2 | 2 | 252 | Rusheen MCDONALD |
JAM |
46.02 Q PB | |
| 5 | 3 | 1 | 229 | Attila MOLNÁR |
HUN |
46.08 Q NR | |
| 6 | 3 | 2 | 168 | Matěj KRSEK |
CZE |
46.48 Q | |
| 7 | 4 | 2 | 354 | Rok FERLAN |
SLO |
46.61 PB | |
| 8 | 4 | 1 | 375 | Jereem RICHARDS |
TTO |
46.64 SB | |
| 9 | 5 | 1 | 308 | Dubem NWACHUKWU |
NGR |
46.69 | |
| 10 | 5 | 2 | 132 | Lucas CARVALHO |
BRA |
47.38 | |
| 11 | 6 | 1 | 101 | Franko BURRAJ |
ALB |
47.78 | .771 |
| 12 | 6 | 2 | 339 | Omar ELKHATIB |
POR |
47.78 | .780 |
ms - Milliseconds - shown when two or more competitors finish with the same time down to hundredths of a second