The diminutive Karoo Prinia (adults weigh only about 9g) inhabits Karoo scrublands and fynbos both in flatlands and in mountainous areas, often at or near drainage lines and wetlands, and is being seen more and more in gardens and plantations of alien vegetation as well. They feed almost exclusively on insects and other invertebrates.
Pairs of Karoo Prinia defend their territories year-round. They build an oval grass nest with a side entrance deep in a dense bush or shrub and lined with a dense layer of soft plant material and fur. They breed almost throughout the year, with a distinct peak in spring and early summer. The female alone incubates the clutch of 1-5 eggs for a period of about two weeks but the chicks are cared for by both parents after hatching. They fledge about two weeks after hatching.
Despite noting that their population is probably declining due to grazing pressure, the IUCN describes the Karoo Prinia as being common to abundant throughout its range, and considers it of least concern. The Karoo Prinia occurs in Lesotho, South Africa (Free State, Western, Eastern and Northern Cape) and marginally into Namibia.