Tetu is a sub-county in Nyeri County, Kenya, located west of Nyeri town, the county capital. The same name is used for the local electoral constituency, Tetu Constituency.
As of 2020, Tetu had a total population of 80,453, with a population density of 378 people per square kilometre. The area is predominantly a rural division and does not contain any major central township.
Its larger shopping centres, which include substantial markets, are Muthinga, Gichira, Ithekahuno and Wamagana.