This paper introduces Xanthomelon amurndamilumilasp. nov., a newly-discovered land snail species inhabiting the North East Isles, offshore from Groote Eylandt (= Ayangkidarrba), north-western Gulf of Carpentaria, in the Northern Territory, Australia. Specimens of this species were first collected during the 2021 Bush Blitz expedition to Groote Eylandt, a large offshore archipelago previously unexplored for land snails. The taxonomic status of the new species was established through a comprehensive analysis of comparative morphology and mitochondrial genetics: X. amurndamilumila forms a maximally supported clade closely related to X. arnhemense and is characterised by a unique combination of morphological characteristics, including smaller shell size, distinctive sculpture of collabral ridges and specific features of its reproductive anatomy. The genetic divergence and phylogenetic relationships suggest historical isolation. While the discovery of X. amurndamilumilasp. nov. enriches our understanding of land snail diversity in the Northern Territory, its conservation status is of concern on North East Island because of habitat degradation caused by feral deer.