The two largest ethnic groups reported in Nunu Kumba were the Oromo (98.88%), and the Amhara (1.06%); all other ethnic groups made up 0.06% of the population.
In Nunu Kumba, the Oromo accounted for 98.88% of the reported ethnic groups, while the Amhara comprised 1.06%. The remaining 0.06% belonged to other ethnic groups.