The men's 800 metres event at the 2017 European Athletics U23 Championships was held in Bydgoszcz, Poland, at Zdzisław Krzyszkowiak Stadium on 14 and 16 July.
| Gold | Andreas Kramer | |
| Silver | Daniel Rowden | |
| Bronze | Marc Reuther |
14 July[1]
Qualification rule: First 2 (Q) and the next 2 fastest (q) qualified for the final.
| Rank | Heat | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|---|
| 1 | 2 | align=left | align=left | 1:46.93 | Q, PB | |||
| 2 | 2 | align=left | align=left | 1:47.02 | Q | |||
| 3 | 2 | align=left | align=left | 1:47.08 | q, PB | |||
| 4 | 2 | align=left | align=left | 1:47.16 | q, PB | |||
| 5 | 2 | align=left | align=left | 1:47.31 | ||||
| 6 | 1 | align=left | align=left | 1:47.51 | Q | |||
| 7 | 1 | align=left | align=left | 1:47.69 | Q, SB | |||
| 8 | 1 | align=left | align=left | 1:47.92 | ||||
| 9 | 2 | align=left | align=left | 1:49.22 | ||||
| 10 | 2 | align=left | align=left | 1:49.40 | PB | |||
| 11 | 1 | align=left | align=left | 1:49.48 | ||||
| 12 | 3 | align=left | align=left | 1:49.50 | Q | |||
| 13 | 3 | align=left | align=left | 1:49.71 | Q | |||
| 14 | 1 | align=left | align=left | 1:49.85 | ||||
| 15 | 3 | align=left | align=left | 1:49.92 | ||||
| 16 | 3 | align=left | align=left | 1:50.38 | ||||
| 17 | 3 | align=left | align=left | 1:50.72 | ||||
| 18 | 3 | align=left | align=left | 1:51.33 | ||||
| 19 | 1 | align=left | align=left | 1:51.75 | ||||
| 20 | 1 | align=left | align=left | 1:53.03 | ||||
| 21 | 3 | align=left | align=left | 1:53.13 |
16 July[2]
| Rank | Name | Nationality | Time | Notes | |||
|---|---|---|---|---|---|---|---|
| align=left | align=left | 1:48.15 | |||||
| align=left | align=left | 1:48.16 | |||||
| align=left | align=left | 1:48.66 | |||||
| 4 | align=left | align=left | 1:48.92 | ||||
| 5 | align=left | align=left | 1:49.19 | ||||
| 6 | align=left | align=left | 1:49.81 | ||||
| 7 | align=left | align=left | 1:50.02 | ||||
| 8 | align=left | align=left | 1:59.93 |