OBJECTIVE: The aim of this study was to describe the incidence of heat-related illness among workers in British Columbia (BC), Canada, 2001-2020. METHODS: Cases of heat-related illness occurring among workers aged 15 years and older were identified from accepted lost-time claims from WorkSafeBC, the provincial workers' compensation board. Incidence rates were calculated using monthly estimates of the working population from Statistics Canada's Labour Force Survey as the denominator. RESULTS: Between 2000 and 2020, there were 528 heat-related illness claims, corresponding to a rate of 1.21 (95% confidence interval, 1.10-1.31) claims per 100,000 workers. Eighty-four percent of claims occurred between June and August. Rates were higher among male workers, younger workers, and among those working in occupations related to primary industry; trades, transport, and equipment operators; and processing, manufacturing, and utilities. CONCLUSIONS: In BC, lost-time claims for heat-related illness occurred disproportionately among certain subgroups of the workforce.