400m Boys Final A ; Official result since 18:41
| Rank | Lane | ID | Name | PB | Team | Cat | Result | Info | Video |
| 1 | 4 | 115 | Placek Tadeas | Brno | 49.83 | ||||
| 2 | 3 | 190 | Chen Jian-rong | New Taipei -city | 51.46 | ||||
| 3 | 6 | 204 | Chang Ting-hao | Taoyuan City | 51.49 | ||||
| 4 | 1 | 119 | Kalamees Karl August | Tartu | 51.65 | ||||
| 5 | 7 | 208 | Barahem Rachan | Bangkok | 51.82 | ||||
| 6 | 8 | 193 | Jiang Yu-cheng | New Taipei -city | 52.24 | ||||
| 7 | 2 | 153 | Talalas Nedas | Kaunas | 52.41 | ||||
| 8 | 5 | 206 | Sribu Aekalak | Bangkok | 52.69 |