2016 IAAF World U20 Championships – Men's 400 metres
The men's 400 metres event at the 2016 IAAF World U20 Championships was held at Zdzisław Krzyszkowiak Stadium on 20, 21 and 22 July.
Medalists
Records
Results
Heats
Qualification: First 3 of each heat and the 6 fastest times qualified for the semifinals.| Rank | Heat | Name | Nationality | Time | Note |
| 1 | 1 | Geoffrey Kiprotich | 46.23 | Q, PB | |
| 2 | 3 | Baboloki Thebe | 46.25 | Q | |
| 3 | 6 | Karabo Sibanda | 46.34 | Q | |
| 4 | 5 | Kahmari Montgomery | 46.46 | Q | |
| 5 | 4 | Abdalelah Haroun | 46.51 | Q | |
| 6 | 2 | Christopher Taylor | 46.73 | Q | |
| 7 | 5 | Myles Banfield | 46.77 | Q, PB | |
| 8 | 2 | Kazuki Matsukiyo | 46.78 | Q | |
| 9 | 6 | Jamal Walton | 46.83 | Q | |
| 10 | 4 | Sean Bailey | 46.83 | Q | |
| 11 | 4 | Cameron Chalmers | 46.91 | Q | |
| 12 | 6 | Iván Núñez | 46.96 | Q | |
| 13 | 3 | Luis Charles | 47.09 | Q | |
| 14 | 6 | Edwin Ngeeti | 47.11 | q | |
| 15 | 2 | Anthony Zambrano | 47.18 | Q | |
| 16 | 2 | Tymoteusz Zimny | 47.20 | q | |
| 17 | 1 | Wilbert London III | 47.23 | Q | |
| 18 | 2 | Taha Hussein Yaseen | 47.31 | q | |
| 19 | 3 | Naoki Kitadani | 47.32 | Q | |
| 20 | 1 | Moussa Ali Issa | 47.39 | Q | |
| 21 | 6 | Vladimir Aceti | 47.62 | q | |
| 22 | 5 | Wu Yuang | 47.65 | Q | |
| 23 | 2 | Jochem Dobber | 47.67 | q | |
| 24 | 6 | David Šalamon | 47.79 | q | |
| 25 | 1 | Mo Il-hwan | 47.82 | ||
| 26 | 4 | Nathan Friginette | 47.91 | ||
| 27 | 3 | Brayan Lopez | 47.92 | ||
| 28 | 1 | Mihai Cristian Pislaru | 48.01 | ||
| 29 | 5 | Derrick Mokaleng | 48.04 | ||
| 30 | 4 | Henri Delauze | 48.15 | ||
| 31 | 5 | Lawson Power | 48.36 | ||
| 32 | 6 | Joshua St. Clair | 48.39 | ||
| 33 | 5 | Charles Devantay | 48.42 | ||
| 34 | 3 | Kinard Rolle | 48.60 | ||
| 35 | 6 | Andile Lusenga | 48.67 | ||
| 36 | 2 | Vitsanu Phosri | 49.30 | SB | |
| 37 | 1 | Gezahegn Ababu | 49.54 | ||
| 38 | 4 | Kashief King | 50.06 | ||
| 39 | 2 | Alessandro Gasperoni | 50.48 | ||
| 3 | Dawid Kapała | ||||
| 1 | Samson Oghenewegba Nathaniel | ||||
| 3 | Gemechu Alemu | ||||
| 4 | Ojo Sunday Fatoyinbo | ||||
| 5 | Abdallah Djimet Souleyman |
Semifinals
Qualification: First 2 of each heat and the 2 fastest times qualified for the final.| Rank | Heat | Name | Nationality | Time | Note |
| 1 | 1 | Karabo Sibanda | 45.15 | Q | |
| 2 | 3 | Geoffrey Kiprotich | 45.38 | Q | |
| 3 | 3 | Wilbert London III | 45.49 | Q | |
| 4 | 2 | Abdalelah Haroun | 45.55 | Q | |
| 5 | 1 | Kahmari Montgomery | 45.71 | Q | |
| 6 | 1 | Anthony Zambrano | 45.81 | q, PB | |
| 7 | 1 | Naoki Kitadani | 46.41 | q, PB | |
| 8 | 3 | Cameron Chalmers | 46.51 | ||
| 9 | 3 | Christopher Taylor | 46.60 | ||
| 10 | 1 | Jamal Walton | 46.61 | ||
| 11 | 2 | Kazuki Matsukiyo | 46.69 | Q | |
| 12 | 3 | Wu Yuang | 46.83 | ||
| 13 | 2 | Iván Núñez | 47.00 | ||
| 14 | 1 | Sean Bailey | 47.09 | ||
| 15 | 3 | Tymoteusz Zimny | 47.14 | PB | |
| 16 | 2 | Jochem Dobber | 47.22 | ||
| 17 | 1 | Taha Hussein Yaseen | 47.26 | ||
| 18 | 2 | Luis Charles | 47.33 | ||
| 19 | 1 | Vladimir Aceti | 47.41 | ||
| 20 | 3 | Myles Banfield | 47.46 | ||
| 21 | 2 | Edwin Ngeeti | 47.51 | ||
| 22 | 3 | David Šalamon | 47.51 | PB | |
| 2 | Baboloki Thebe | R163.3 | |||
| 2 | Moussa Ali Issa |
Final
| Rank | Lane | Name | Nationality | Time | Note |
| 6 | Abdalelah Haroun | 44.81 | SB | ||
| 7 | Wilbert London III | 45.27 | PB | ||
| 5 | Karabo Sibanda | 45.45 | |||
| 4 | 4 | Geoffrey Kiprotich | 45.64 | ||
| 5 | 8 | Kahmari Montgomery | 46.48 | ||
| 6 | 2 | Anthony Zambrano | 46.50 | ||
| 7 | 9 | Kazuki Matsukiyo | 46.69 | PB | |
| 8 | 3 | Naoki Kitadani | 47.15 |