| Kajen | |
| Pushpin Map: | Indonesia_Java#Indonesia |
| Pushpin Label Position: | bottom |
| Pushpin Mapsize: | 310 |
| Pushpin Map Caption: | Location in Central Java and Indonesia |
| Subdivision Type: | Country |
| Subdivision Name: |  Indonesia |
| Subdivision Type1: | Province |
| Subdivision Name1: | Central Java |
| Subdivision Type2: | Regency |
| Subdivision Name2: | Pekalongan Regency |
| Subdivision Type3: | District |
| Subdivision Name3: | Kajen District |
| Unit Pref: | Imperial |
| Population As Of: | 2020 Census |
| Population Note: | [1] |
| Population Total: | 73067 |
| Population Density Km2: | auto |
| Population Blank1 Title: | Ethnicities |
| Timezone: | Indonesia Western Standard Time |
| Utc Offset: | +7 |
| Coordinates: | -7.0345°N 109.5766°W |
| Elevation M: | 35 |
Kajen is a town in Central Java, Indonesia and the administrative centre of the Pekalongan Regency in the province of Central Java. Its population was 58,048 at the 2010 Census[2] and 73,067 at the 2020 Census.[3]
Kajen has a tropical rainforest climate (Af) with moderate rainfall from June to September and heavy to very heavy rainfall from October to May.