Municipality of Nyamira came into existence by the implementation of the Urban Areas and Cities Act No 13 of 2011(amended). The act provides that all urban areas designated as the County Headquarter be upgraded to Municipality status despite not meeting the minimum threshold of infrastructure and population. In 2018, H.E. The Governor declared Nyamira a Municipality in accordance with the provisions of the approved Nyamira Municipality charter.

Municipality of Nyamira covers an area of approximately 155 Km2. According to the 2009 Kenya Population Housing Census (KPHC), Nyamira had an estimated population of 164,101. However, Nyamira Municipality’s updated estimate population shall be adequately determined once the next census captures data for all the residents within the established boundary.