Birkenes is a municipality in Aust-Agder county, Norway. It is located in the traditional district of Sørlandet. The village of Birkeland is the administrative center and about half of the municipality's residents live there. Birkeland is 30 kilometres (19 mi) from Kristiansand and 13 kilometres (8.1 mi) from Lillesand.
The municipality borders Kristiansand and Vennesla municipalities in Vest-Agder county and Iveland, Evje og Hornnes, Froland, Grimstad, and Lillesand municipalities in Aust-Adger.