Background Scrub typhus is a major cause of febrile illness in Southeast Asia, with particularly high burdens reported in northern Thailand. Environmental exposures and use of preventive measures remain incompletely understood. Methods We conducted a population-based cross-sectional serosurvey in Chiang Rai province, Thailand in 2022-2023. Adults aged [≥]15 years from 74 villages were selected by two-stage random sampling and interviewed regarding demographic characteristics, agricultural and domestic exposures, and preventive behaviours. IgG antibodies against Orientia tsutsugamushi were measured using a Luminex xMAP Intelliflex(R) platform. Mixed-effects logistic regression models stratified by ethnicity (highland people vs Thai) were used to identify factors associated with seropositivity, with village as a random intercept. Results Among 1,194 participants with valid serology, seroprevalence was higher among highland people than Thai ones (60% vs 13%, p