AbstractObjectiveA substantial number of workers’ experience mistreatment in the workplace, impacting workers' health and companies' functioning. Vulnerability of those with lower income has been reported, yet little is known about mistreatment during COVID‐19. This study aims to examine whether workers in financial distress are particularly prone to mistreatment at the workplace with reference to pandemic‐related infection prevention measures.MethodsAn internet‐based, year‐long prospective cohort study was conducted from 2020 to 2021. Participants were recruited from workers aged 20 and 65 years and currently employed at baseline. In total, 27 036 were included in the analysis and 18 170 responded to the follow‐up survey. The odds ratio (OR) of mistreatment at the workplace regarding COVID‐19 associated with the financial condition at baseline was estimated using multilevel logistic regression analysis nested by participant residence.ResultsCompared with workers in a comfortable financial condition, those under financial stress showed significantly higher ORs of mistreatment (age‐ and sex‐adjusted model: 2.08, 95% confidence interval [CI] 1.75–2.47,P< .001, model adjusted for socioeconomic factors: 2.14, 95% CI 1.79–2.55,P< .001).ConclusionWorkers in financial distress were shown to be vulnerable to mistreatment at work regarding infection prevention measures in the COVID‐19 pandemic, underscoring a double burden of poverty and mistreatment. The perspective of vulnerable groups needs to be taken into account when implementing countermeasures against emerging infectious diseases, such as COVID‐19. As unfair treatment in the workplace might distort vulnerable employees' reactions to infection control (e.g., hiding infection), financial deprivation should be considered a public health issue.