The remaining large patches of lowland forest in Tanintharyi, southern Myanmar, are the last global stronghold for the Endangered Gurney's pitta Hydrornis gurneyi. Except for a few individuals, the remaining population is now restricted to this forest, below 150 m altitude, mostly within the Nga Wun, Lenya, and Parchan Reserved Forests. However, as in much of South-east Asia, Tanintharyi has been subjected to extensive deforestation, particularly for oil palm cultivation. The aim of this research was to determine the extent of remaining habitat suitable for Gurney's pitta. During January–October 2016 we revisited 142 locations (of 147) where the species was detected during 2003–2012, and found it in only 41 of those locations (29%); in all other locations the forest had been cleared. We measured the decline of suitable habitat since 1999 by examining all available intact forest in areas with elevations < 150 m and slope < 10 °. In less than 2 decades suitable habitat has declined from 3,225 to 656 km2 (80%). Protection of remaining lowland forest is now critical. Although the expansion of oil palm cultivation has slowed since its peak in the early 2000s, two national parks proposed by the Myanmar government in 2002, which would potentially offer legal protection for most of the remaining Gurney's pitta habitat, remain on hold because of political uncertainties. We recommend an alternative conservation approach for this species, based on an Indigenous Community Conserved Area model, and further research to improve knowledge of the species and to determine how it could be saved from extinction.