| Image Coa: | DEU Alt Duvenstedt COA.svg |
| Coordinates: | 54.3583°N 9.6444°W |
| Image Plan: | Alt Duvenstedt in RD.png |
| State: | Schleswig-Holstein |
| District: | Rendsburg-Eckernförde |
| Amt: | Fockbek |
| Elevation: | 8 |
| Area: | 20.43 |
| Postal Code: | 24791 |
| Area Code: | 04335, 04336, 04338 |
| Licence: | RD |
| Gemeindeschlüssel: | 01 0 58 003 |
| Website: | www.fockbek.de |
| Mayor: | Peter Eichen |
Alt Duvenstedt is a municipality in the district of Rendsburg-Eckernförde, in Schleswig-Holstein, Germany.