The Sunda, or Sundaland, clouded leopard inhabits tall, primary forest, but appears able to survive in areas of partly logged forest, albeit in lower numbers. It is restricted to the islands of Borneo and Sumatra.

The species was formerly considered to be a subspecies of the clouded leopard Neofelis nebulosa, but was elevated to species status in 2006.

Its build is stocky, with strong, muscular legs, and its tail is long. Its head is relatively small compared to its body size, with small, rounded ears. Its fur is patterned with large, blotchy patches of dark fur.

This animal is nocturnal, secretive and generally solitary in nature, and little is known of its ecology. It is an excellent tree climber, and in areas where the forest is well connected it need rarely come to ground.

The species consumers a variety of medium-size mammal prey including various species of porcupine, civet, deer and pig.

The Bornean form, Neofelis diardi borneensis, occurs in suitable forest in elevations ranging from the lowlands to around 1500 metres. This is the largest species of wild cat in Borneo.

The Sumatran form, Neofelis diardi diardi, appears to be restricted to hilly and montane regions of the main mountain spine which runs parallel to the west coast. In Sumatra its size is exceeded by another cat, the Sumatran tiger.

The species as a whole is categorized as 'vulnerable' due to a decreasing population, and constant shrinking of its forest habitat. Sightings of the species are rare, but a better understanding of its distribution and population size has been made by the use of trail cameras (camera traps).

In Borneo this species occurs in parts of Malaysian Borneo (Sarawak, Sabah), Brunei and the Indonesian territory of Kalimantan. On the Indonesian island of Sumatra it is restricted mainly to the west.