Kilsund is a village in Arendal municipality in Agder county, Norway. The village is located on the island of Tverrdalsøya, although the village has grown over the bridge onto the nearby island of Flostaøya a short distance to the south. The village lies about 6.5 km northeast of the village of Strengereid, about 10 km northeast of the village of Eydehavn, about 16 km northeast of the town of Arendal, and about 8 km south of the town of Tvedestrand. Kilsund has two small villages located just to the north and east: Staubø and Holmsund. The 0.93 km2 village has a population (2016) of 717 which gives the village a population density of 771 PD/km2.