Objective This study aimed to explore the feasibility of cognitive-behavioral model hypochondriasis regarding coronavirus disease-2019 (COVID-19) among firefighters. In addition, we examined the possible role of their grief reaction and intolerance of uncertainty in the model of COVID-related hypochondriasis. Methods An anonymous online survey was done on October 27–28, 2022, among firefighters who witnessed people’s death. Demo-graphic characteristics were collected, and their psychological states were assessed using rating scales such as the Obsession with COV-ID-19 Scale (OCS), Coronavirus Reassurance-Seeking Behaviors Scale (CRBS), Fear of COVID-19 Scale (FCV-19S), Pandemic Grief Scale (PGS), and Intolerance of Uncertainty Scale–12 (IUS-12). Results Their OCS score was expected by the CRBS (β=0.30, p<0.001), FCV-19S (β=0.10, p<0.001), PGS (β=0.29, p<0.001), and IUS-12 (β=0.04, p=0.024) (F=134.5, p<0.001). The COVID-related cognitive-behavioral model of hypochondriasis was feasible among fire-fighters who witnessed people’s death. Their pandemic grief reaction and intolerance of uncertainty directly influenced their preoccupa-tion with coronavirus, and viral anxiety and coronavirus reassurance-seeking behavior mediated the relationship. Conclusion Firefighters’ viral anxiety and coronavirus reassurance-seeking behavior mediated the influence of pandemic grief reaction or intolerance of uncertainty on the preoccupation with coronavirus.