| Coordinates: | 53.8167°N 65°W |
| Image Plan: | Siemz-Niendorf in NWM 2011.svg |
| State: | Mecklenburg-Vorpommern |
| District: | Nordwestmecklenburg |
| Amt: | Schönberger Land |
| Elevation: | 28 |
| Area: | 26.21 |
| Postal Code: | 23923 |
| Area Code: | 038828 |
| Licence: | NWM |
| Gemeindeschlüssel: | 13 0 74 094 |
Siemz-Niendorf is a municipality in the Nordwestmecklenburg district, in Mecklenburg-Vorpommern, Germany. It was created with effect from 26 May 2019 by the merger of the former municipalities of Groß Siemz and Niendorf.