Kajen is an administrative district (kecamatan) and a town (kelurahan) located in the Central Java Province of Indonesia. It serves as the administrative center for the Pekalongan Regency. The area covers a total land size of 75.15 km2.
The district is subdivided into one town, known as Kajen, and 24 rural villages (desa), all of which share the postcode 51161. According to census data, the population grew from 58,048 in 2010 to an estimated 80,919 by mid-2025. As of mid-2023, the specific town of Kajen had a population of 2,982 inhabitants.