It is found in large parts of Central Africa (Cameroon, southeastern Central African Republic, Equatorial Guinea, Gabon, the Republic of the Congo, and northeastern Democratic Republic of the Congo), extending into south-easternmost West Africa (Nigeria).

The type locality is Cap Saint Jean in Equatorial Guinea.

[2] Populations from the Upper Guinean Forests of West Africa between Ghana and Sierra Leone previously allocated to this species were in 2008 described as a new species, Cardioglossa occidentalis.

[2][3] Common name silver long-fingered frog has been coined for Cardioglossa leucomystax.

[3] Cardioglossa leucomystax, defined as including Cardioglossa occidentalis, occur in lowland and lower montane forests, including secondary forests and heavily degraded habitats.