Fiji’s native Lasioglossum bees are becoming a model taxon for research on climate resilience, due to their rapid diversification and an unusual concentration of species richness at higher elevations. However, their narrow highland habits and impending threats from climate change could push 80–90% of Fiji’s bee diversity higher until they “fall off” the top of the mountain. A dedicated, multidisciplinary research effort has illuminated much of these bee’s biology, from phylogenetic relationships to physiological tolerance of thermal conditions. However, how the molecular makeup of these bees might mediate thermal tolerance remains unknown. Here, we examine both the abundance of proteostasis machinery and the thermal proteome profile to assess the thermostability of several species of Fijian Lasioglossum. We report that the generalist species L. fijiense, which can live across the entire elevational range of Viti Levu, has a higher abundance of thermoregulatory proteins compared to the elevational specialists limited to the montane forests of Fiji. Similarly, L. fijiense proteins were more thermostable overall, when making homologous pairwise comparisons with the specialist species. Together, these findings suggest inherent proteome-wide differences in these species that alter their vulnerability to warmer climates at the molecular level, either as a cause or consequence of their inhabiting specific environmental niches present in unique parts of Fiji. This research is the first application of thermal proteomic profiling to questions of climate change and the new knowledge generated here will inform future efforts to understand the mechanisms behind climate resilience.