The giant muntjac Muntiacus vuquangensis is a Critically Endangered ungulate that was first described by science in the early 1990s. The species’ current known distribution extends along the Annamite Mountains in Laos and Vietnam. Here, we report the first confirmed record of the giant muntjac in Cambodia. We recorded a camera-trap photograph of a male giant muntjac in Virachey National Park in northeastern Cambodia. Our record likely represents an isolated population near the western edge of the species’ distribution, about 300 km from the closest confirmed populations.