To quantify the cost of hospital separations attributable to environmental risk factors in the Northern Territory, including for Indigenous and remote subgroups.A retrospective cross-sectional secondary data analysis of hospital separations data. Data collection, analysis and presentation were guided by our Indigenous Steering Committee.All episodes of care from 1 July 2021 to 30 June 2022 with an inpatient separation (discharge, transfer, death) from NT public hospitals were included. Non-inpatient episodes of care (outpatient, emergency department and primary care presentations) were excluded.Individual hospital separations were classified as environmentally attributable if the International statistical classification of diseases and related health problems, 10th revision, Australian modification (ICD-10-AM) code for their primary diagnosis matched an included disease. Included diseases were based on environmental attributable fractions previously generated for the Kimberley region, contextualised to the NT. Costs were assigned to individual hospital separations based on activity-based funding allocations.Environmental risk factors contributed more than $72 million to inpatient hospital costs in the NT over 1 year. Environmental risks disproportionately affected children aged 0-4 years ($10.9 million), Indigenous people ($47.2 million) and those in remote areas ($41.7 million). Skin disease made up the largest contribution by a single disease ($26.4 million). The two largest categories of environmental risk were "water quality, sanitation and hygiene" and "home condition", together contributing $37.3 million in costs.Quantifying the economic impact of preventable environmental risk in the NT bolsters the argument for strengthening environmental health initiatives. Health disparities between groups reflect the interconnectedness of environmental, social and cultural determinants of health. Targeted interventions to reduce inequities in housing, sanitation and water quality are needed. Delivering on existing environmental health commitments through meaningful partnerships and coordinated action across sectors such as housing and education is essential, particularly within the Northern Territory Implementation Plan on Closing the Gap.