Willi Willi National Park conserves a wide diversity of wet forest vegetation including rainforest, one of the most significant stands of Antarctic beech forest in Australia, and many threatened plant and animal species. A large proportion of the park, 23 309 hectares, is declared as the Willi Willi Wilderness.
Willi Willi National Park contains places of cultural significance to the Dunghutti Aboriginal people. It also contains evidence of past forestry activities, including the Banda Banda arboretum. The boundaries of the park include the former Banda Banda Flora Reserve which is part of the Gondwana Rainforests of Australia World Heritage Area.