The women's 400 metres 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 and 17 July.
| Gold | Kseniya Ustalova | |
| Silver | Kseniya Zadorina | |
| Bronze | Anna Sedova |
17 July
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| align=left | align=left | | 51.74 | ||||
| align=left | align=left | | 51.76 | ||||
| align=left | align=left | | 52.58 | ||||
| 4 | align=left | align=left | 52.59 | ||||
| 5 | align=left | align=left |  | 52.81 | |||
| 6 | align=left | align=left |  | 52.94 | |||
| 7 | align=left | align=left |  | 53.43 | |||
| 8 | align=left | align=left |  | 53.56 |
16 July
Qualified: first 3 in each heat and 2 best to the Final
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | 52.70 | Q | |||
| 2 | align=left | align=left | | 52.76 | Q | ||
| 3 | align=left | align=left | | 53.05 | Q | ||
| 4 | align=left | align=left | | 53.42 | q | ||
| 5 | align=left | align=left |  | 53.85 | |||
| 6 | align=left | align=left |  | 54.04 | |||
| 7 | align=left | align=left |  | 54.32 | |||
| 8 | align=left | align=left | | 55.92 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 52.59 | Q | ||
| 2 | align=left | align=left | | 52.68 | Q | ||
| 3 | align=left | align=left | | 52.72 | Q | ||
| 4 | align=left | align=left | | 52.98 | q | ||
| 5 | align=left | align=left |  | 54.04 | |||
| 6 | align=left | align=left |  | 54.25 | |||
| 7 | align=left | align=left | | 54.80 | |||
| 8 | align=left | align=left |  | 55.68 |
16 July
Qualified: first 3 in each heat and 4 best to the Semifinals
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 53.55 | Q | ||
| 2 | align=left | align=left | | 53.65 | Q | ||
| 3 | align=left | align=left | | 54.34 | Q | ||
| 4 | align=left | align=left | | 54.46 | q | ||
| 5 | align=left | align=left | | 55.41 | |||
| 6 | align=left | align=left | | 57.75 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 53.02 | Q | ||
| 2 | align=left | align=left | | 53.43 | Q | ||
| 3 | align=left | align=left | | 53.49 | Q | ||
| 4 | align=left | align=left | | 53.64 | q | ||
| 5 | align=left | align=left | | 54.22 | q | ||
| 6 | align=left | align=left | 54.84 | ||||
| 7 | align=left | align=left |  | 57.65 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | 53.81 | Q | |||
| 2 | align=left | align=left | | 54.18 | Q | ||
| 3 | align=left | align=left | | 54.36 | Q | ||
| 4 | align=left | align=left | | 54.67 | q | ||
| 5 | align=left | align=left | | 54.97 | |||
| 6 | align=left | align=left | 56.28 |
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| 1 | align=left | align=left | | 53.43 | Q | ||
| 2 | align=left | align=left | | 53.62 | Q | ||
| 3 | align=left | align=left | | 54.00 | Q | ||
| 4 | align=left | align=left |  | 55.22 | |||
| 5 | align=left | align=left | | 55.41 | |||
| 6 | align=left | align=left | | 55.94 |
According to an unofficial count, 25 athletes from 16 countries participated in the event.
(1) (1) (1) (3) (1) (3) (1) (2) (2) (3) (2) (1) (1)