Vennesla is a municipality in Agder county, Norway. It is located in the traditional district of Sørlandet. The administrative centre of the municipality is the village of Vennesla. Other villages in Vennesla include Grovane, Hægeland, Homstean, Mushom, Øvre Eikeland, Øvrebø, Røyknes, and Skarpengland. Vennesla lies about north of the city of Kristiansand in the Otra river valley.
The municipality is the 242nd largest by area out of the 356 municipalities in Norway. Vennesla is the 78th most populous municipality in Norway with a population of 15,123. The municipality's population density is and its population has increased by 11.3% over the previous 10-year period.
The parish of Vennesla was established as a municipality in 1864 when it was separated from the larger municipality of Øvrebø. Initially, Vennesla had 1,103 residents. During the 1960s, there were many municipal mergers across Norway due to the work of the Schei Committee. On 1 January 1964, Vennesla (population: 7,321) was merged with most of the neighboring municipality of Øvrebø (population: 925) and with all of another neighboring municipality, Hægeland (population: 849) which created a new, much larger municipality of Vennesla. On 1 January 1978, a small area of Vennesla (population: 10) was transferred to neighboring Songdalen municipality. Then again on 1 January 1984, the unpopulated Hauglandsvatnet area was transferred from Vennesla to Songdalen municipality. On 1 January 1990, the unpopulated Røssebrekka area, just east of the village of Vennesla was transferred from Kristiansand municipality to Vennesla.
The municipality (originally the parish) is named after the old Vennesla farm (Vendilslá) since the first Vennesla Church was built there. The first element is vendil which comes from the word vǫndr which means "small twig". This may have been an old name for an arm of Venneslafjorden. The last element is lá which means "swamp" or "shallow water".
The coat of arms was adopted on 15 May 1971.