Kayan Mentarang National Park (Indonesian: Taman Nasional Kayan Mentarang) is a densely forested national park located in the Indonesian province of North Kalimantan, on the island of Borneo.

Kayan Mentarang National Park is located at the border between Indonesia and Malaysia.

Until recently it has been difficult for tourists to enter this huge National Park, with difficulties often encountered at the local rural Malaysian-Indonesian border checkpoint.

Animals found in the park include the mammals such as Malayan pangolin, the long-tailed macaque, the proboscis monkey, the Bornean gibbon, the greater slow loris, the western tarsier, the clouded leopard, the marbled cat, the flat-headed cat, the Oriental small-clawed otter, the sun bear, and the Hose's palm civet.

Archaeological remains in the park including stone tools and graves indicate that the area was inhabited over 350 years ago.