Here, we report the first attempt to use isotope geochemistry to improve understanding of the experiences of Indigenous Australians living on the colonial frontier in late 19th century CE Australia. In the study, we analysed strontium (87Sr/86Sr), carbon (δ13C), and oxygen (δ18O) isotope ratios from the tooth enamel and dentine of six individuals who died in Normanton, Queensland, in the 1890s. The study was a collaboration between scientists and the local Traditional Owners, the Gkuthaarn and Kukatj people, and was carried out to promote truth and reconciliation. The enamel 87Sr/86Sr results suggest that the individuals moved to Normanton from three geologically distinct regions during the period of European expansion into the Gulf of Carpentaria, Cape York. This is consistent with the oral histories and historical documents, which suggest that many Indigenous people in the Gulf Country were displaced to camps on the outskirts of towns like Normanton because of European settlement. The δ13C values we obtained indicate that the individuals mostly ate C4 plants and/or C4-plant-consuming herbivores. When combined with the fact that some of the individuals’ teeth had dental caries, this suggests that the individuals may have had regular access to introduced foods. The enamel δ18O values are high compared to an international comparative sample, at 0.72–4.69‰ VPDB. We suspect the elevated values are due to a combination of a high degree of preferential loss of 16O through evaporation of surface water, the amount effect associated with the Australian monsoon, and high prevalence of introduced infectious diseases. Together, the results of our study demonstrate that isotopic analysis of human remains has the potential to further illuminate the effects of European colonisation on Indigenous people in Australia. Perhaps most importantly in connection with this, our study’s results show that isotopic analyses of human remains can provide surprisingly detailed information about the lives of a category of Indigenous Australians who rarely appear in the documents written by early ethnographers and colonial officials—subadults. That the analysis of the skeletal remains of Indigenous Australians can now contribute to the truth and reconciliation process is an unexpected, interesting, and welcome development in the story of bioarchaeology in Australia.