This paper describes the protracted nomination to the UNESCO World Heritage (WH) List of the Keang Krachan Forest Complex, Thailand and the issues it exposed. The complex was inscribed in 2021, seven years after it was first nominated, despite ongoing conflict with indigenous Karen hunter-gatherer communities. The nomination was referred back to the state party by the WH Committee in 2015, 2016 and 2019 for reasons related to inconclusive and out-of-date ecological information, and human rights issues associated with the forced resettlement of Karen hill tribe people living within its proposed boundaries. In 2020 the nomination was resubmitted during the 4th mandate of the Thai state party on the WH Committee, and the property was inscribed contrary to a formal recommendation to defer the nomination, and despite repeated communications from the Office of the High Commissioner of Human Rights to the WH Centre, the Thai government and the WH Committee seeking resolution of community and human rights issues prior to inscription. Decisions that run contrary to the advice of the WH Committee’s three advisory bodies have become an abiding and troubling aspect of the Committee’s decision-making, reflecting a trend in the politicisation of Committee sessions that has increased over more than 20 years, to a point where it now threatens the integrity of the World Heritage system. This paper examines how the state party pursued its WH ambitions and the impacts this had on particular indigenous Karen communities during national designation and nomination to the WH List. It demonstrates the issues that arise due to legacy nature conservation approaches to the management of extensive natural protected areas.