Pachnessa smetsi is a species of beetle of the family Scarabaeidae. It is found in Cambodia.
Adults reach a length of about 13.6 mm. They have an elongate body. The head is dark brown, and the pronotum has a central band in the shape of a dark brown cross and is very broad yellowish brown laterally. The elytra are black except for the yellowish-brown basal quarter. The antennae and underside are also yellowish-brown. The entire upper surface has a distinct pruinose veil on the pronotum and elytra.
The species is named after one of its collectors, P. Smets.