Horneburg is a Samtgemeinde ("collective municipality") in the district of Stade, in Lower Saxony, Germany. Its seat is in the village Horneburg.
The Samtgemeinde Horneburg consists of the following municipalities:
- Agathenburg
- Bliedersdorf
- Dollern
- Horneburg
- Nottensdorf
53°30′00″N 9°34′59″E / 53.500°N 9.583°E / 53.500; 9.583