The village lies on the Weser River. Due to the reeds that grew there, the area was called "Rohrsen" (a combination of "Rohr" and "Hausen") from earliest times. Originally, the village was part of the County of Wölpe. It was first documented in 1302 when it was sold to Duke Otto the Strict of Brunswick.
During the Thirty Years' War, starting in 1640, fortifications were built near Rohrsen to monitor shipping traffic on the Weser and manned by musketeers. Parts of these fortifications can still be visited today and are located directly on the Weser Cycle Path. Between 1675 and 1679, the Old Fortification was re-equipped with artillery by Prince Johann Friedrich of Calenberg because of the conflicts with the Swedes. Before 1740, the New Fortification, which was strategically more advantageous than the Old Fortification, and the Balger Fortification on the opposite bank were demolished.