Castanopsis densinervia is a tree in the family Fagaceae. The specific epithet ' is from the Latin meaning 'dense nerves', referring to the leaf venation.
Castanopsis densinervia grows as a tree up to tall with a trunk diameter of up to . The greyish bark is smooth. The coriaceous leaves measure up to long. Its ovoid nuts measure up to long.
Castanopsis densinervia is endemic to Borneo. Its habitat is hill dipterocarp to lower montane forests from to elevation.