Angola, Cameroon, Central African Republic, Congo [The Democratic Republic of the], Congo [The Democratic Republic of the], Côte dIvoire, Equatorial Guinea, Gabon, Ghana, Guinea, Liberia, Nigeria, Sierra Leone, Sudan, Togo, Uganda.
Southern Guinea and Sierra Leone east to southern Sudan and western Uganda, and south to north-western Angola and southern Zaire; also Bioko I (Fernando Póo).
 
Population
Estimated population is unknown (2010).
Black-casqued Hornbill (Ceratogymna atrata) [XC492855]
by Andres Angulo Rubiano from Lobeke National Park, Headquarters, Mambele, Cameroon (call, song)
Black-casqued Hornbill (Ceratogymna atrata) [XC718957]
by Deville Tanguy from Kakum National Park, Ghana (call)