| Official Name: | Koyonzo |
| Pushpin Map: | Kenya |
| Mapsize: | 200px |
| Subdivision Type: | Country |
| Subdivision Type1: | County |
| Subdivision Name: | Kenya |
| Subdivision Name1: | Kakamega County |
| Established Date: | 1814 |
| Population As Of: | 2014 |
| Population Urban: | 12000 |
| Population Metro: | 7000 |
| Timezone: | EAT |
| Utc Offset: | +3 |
| Coordinates: | 0°N 34.42°W |
Koyonzo is a settlement in Kenya's Western Province, Kakamega county. It was initially known as Mamboleo due to its early exposure to the long-distance traders from the Mombasa to Buganda Kingdom. Koyonzo was in the Wanga Kingdom which was led by Nabongo Mumia. It is currently located along Mumias-Busia Road, a gateway to Uganda. The town is surrounded by the villages of Ngairwe, Munanziri, Mung'ungu, Mwira, Mirere, Matungu, Ejinja and Lunganyiro.