We describe a new frog species of the genus Cardioglossa from the Upper Guinean forests of West Africa. Cardioglossa occidentalis, new species, is found in primary rainforests in Ghana, Ivory Coast, Guinea, Liberia, and Sierra Leone. We demonstrate that this species is morphologically and genetically distinct from C. leucomystax, the species to which these populations were previously assigned. Cardioglossa occidentalis differs from similar congeners by the following combination of markings: fusion or near fusion of all three dorsal lobes (cephalic, scapular, and lumbar); prominent white line extending anteriorly from arm terminates ventral to eye; dark mask extending posteriorly from eye continues unbroken beyond posterior border of scapular lobe; lateral body covered in very few, large dark spots rimmed with thin white. Cardioglossa occidentalis appears related to C. leucomystax, C. melanogaster, and C. schioetzi. This description brings the number of Cardioglossa species to 16.