The men's 400 metres hurdles event at the 2009 European Athletics U23 Championships was held in Kaunas, Lithuania, at S. Dariaus ir S. Girėno stadionas (Darius and Girėnas Stadium) on 16, 17, and 18 July.
| Gold | Lloyd Gumbs | |
| Silver | Stanislav Melnykov | |
| Bronze | Vincent Vanryckeghem |
18 July
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| align=left | align=left | 49.62 | |||||
| align=left | align=left | | 49.88 | ||||
| align=left | align=left | | 49.90 | ||||
| 4 | align=left | align=left |  | 50.02 | |||
| 5 | align=left | align=left | 50.25 | ||||
| 6 | align=left | align=left | | 50.25 | |||
| 7 | align=left | align=left | 50.61 | ||||
| 8 | align=left | align=left |  | 51.02 |
17 July
Qualified: first 3 each heat and 2 fastest to Final
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 50.36 | Q | ||
| 2 | align=left | align=left | | 50.37 | Q | ||
| 3 | align=left | align=left | 50.67 | Q | |||
| 4 | align=left | align=left | 51.21 | ||||
| 5 | align=left | align=left |  | 51.24 | |||
| 6 | align=left | align=left |  | 51.29 | |||
| 7 | align=left | align=left |  | 52.48 | |||
| align=left | align=left | DNS |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 50.05 | Q | ||
| 2 | align=left | align=left | 50.07 | Q | |||
| 3 | align=left | align=left | 50.12 | Q | |||
| 4 | align=left | align=left | | 50.45 | q | ||
| 5 | align=left | align=left | | 50.48 | q | ||
| 6 | align=left | align=left | 51.31 | ||||
| 7 | align=left | align=left |  | 51.57 | |||
| 8 | align=left | align=left | 51.69 |
16 July
Qualified: first 3 each heat and 4 best to Semifinals
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | 50.83 | Q | |||
| 2 | align=left | align=left | | 51.03 | Q | ||
| 3 | align=left | align=left | | 51.05 | Q | ||
| 4 | align=left | align=left | | 51.08 | q | ||
| 5 | align=left | align=left | | 51.47 | q | ||
| 6 | align=left | align=left |  | 52.73 | |||
| 7 | align=left | align=left |  | 53.02 | |||
| 8 | align=left | align=left |  | 53.34 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 50.66 | Q | ||
| 2 | align=left | align=left | 51.01 | Q | |||
| 3 | align=left | align=left | | 51.63 | Q | ||
| 4 | align=left | align=left | 51.83 | ||||
| 5 | align=left | align=left |  | 51.89 | |||
| 6 | align=left | align=left | | 52.02 | |||
| 7 | align=left | align=left | | 52.02 | |||
| 8 | align=left | align=left | 52.20 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 50.67 | Q | ||
| 2 | align=left | align=left | | 50.70 | Q | ||
| 3 | align=left | align=left | 50.98 | Q | |||
| 4 | align=left | align=left | 51.11 | q | |||
| 5 | align=left | align=left | 51.14 | q | |||
| 6 | align=left | align=left | | 51.64 | |||
| 7 | align=left | align=left | | 52.00 | |||
| 8 | align=left | align=left | 52.54 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 50.97 | Q | ||
| 2 | align=left | align=left | 51.08 | Q | |||
| 3 | align=left | align=left | 51.39 | Q | |||
| 4 | align=left | align=left | | 51.63 | |||
| 5 | align=left | align=left | | 52.35 | |||
| 6 | align=left | align=left |  | 52.35 | |||
| 7 | align=left | align=left |  | 52.68 | |||
| 8 | align=left | align=left |  | 52.75 |
According to an unofficial count, 32 athletes from 21 countries participated in the event.
(1) (1) (1) (1) (3) (1) (2) (1) (1) (1) (3) (1) (1) (3) (1)