While prior studies in human resource management have investigated how employee outcomes have been affected in high-risk workplaces, this study stands out by examining this issue through the role played by COVID-19 as a specific stressor. We explained how employees' perceived health risks due to COVID-19 (CV19PHR) and perceived workplace safety practices (PWSPs) affected job performance via burnout and how PWSPs moderated the CV19PHR–burnout and CV19PHR–JP relationships. We also examined how mindfulness moderated the direct effects of CV19PHR and PWSPs on burnout and JP and the indirect effects of CV19PHR and PWSPs on JP via burnout. We performed three studies using an explanatory sequential mixed-method design. In study 1, a three-phase survey with 987 respondents was conducted to test the hypotheses. In study 2, by analyzing verbatim from 22 informants, the findings of study 1 and some main points concerning mindfulness and PWSPs were explained. In study 3, using data from 12 informants, we investigated how COVID-19 affected individuals differently compared with other high-risk workplaces and whether the impact of COVID-19 on individuals was curvilinear. We demonstrated that employees' CV19PHR was positively correlated with burnout, negatively influencing JP. Moreover, PWSPs reduced burnout, which adversely affected JP. Interestingly, PWSPs positively moderated the CV19PHR–burnout relationship but not the CV19PHR–JP relationship. We also found that mindfulness moderated the CV19PHR–burnout and PWSPs–burnout relationships. Furthermore, mindfulness significantly moderated the mediating effects of burnout on the CV19PHR–JP and PWSPs–JP relationships.