Asker is a district and former municipality located in Akershus, Norway. Situated approximately 20km southwest of Oslo, it forms part of the Greater Oslo Region. The area was originally established as a parish during the Middle Ages before being organized into a formal municipality on January 1, 1838.
In 2020, Asker merged with the traditional Buskerud districts of Røyken and Hurum to form a larger administrative municipality also named Asker. Within this new administrative structure, the original district of Asker constitutes the northern fourth. The town of Asker serves as the administrative center for the expanded municipality.