The Mouse-brown Sunbird (Anthreptes gabonicus) is a species of bird in the Nectariniidae family. It is found in Angola, Burkina Faso, Cameroon, Republic of the Congo, Democratic Republic of the Congo, Ivory Coast, Equatorial Guinea, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Nigeria, Senegal, and Sierra Leone. Its natural habitat is subtropical or tropical mangrove forests.