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) [XC405179]
by Andres Angulo Rubiano from American University of Central Africa (AUCA), Equatorial Guinea (call, also wingbeats)
Black-casqued Hornbill (Ceratogymna atrata) [XC824123]
by Deville Tanguy from Lompole, Bandundu, Mai-Ndombe, Congo (Democratic Republic) (call)