Several studies have examined the impact of the COVID-19 pandemic on healthcare workers’ mental health, but only a few have investigated its detrimental effect on the mental well-being of mental health workers (MHWs). Background: The current study aimed to explore the effect of the fear of COVID-19 (FSV-19) on professional quality of life dimensions, namely compassion satisfaction (CS), burnout (BO), and secondary traumatic stress (STS) in MHWs above and beyond sociodemographic and professional factors. Methods: Hierarchical linear regression models were employed to examine the relationship of extreme FSV-19 with CS, BO, and STS in MHWs (n = 224), after considering sociodemographic variables as potential confounding factors. Extreme FSV-19 was operationalized as a binary variable with a cut-off score of ≥16.5 considered as extreme fear. Results: We found that extreme FSV-19 in MHWs is linked with increased compassion fatigue (BO and STS), and this relationship is exacerbated by younger age in regard to BO and by female gender concerning STS. CS remains unaffected by severe FCV-19, and it is higher in older participants. Conclusion: Organizational support is required to protect MHWs’ mental well-being and ensure the quality of care they provide during prolonged crises, such as the COVID-19 pandemic. Measures that intensify a sense of safety, protection, and control against COVID-19 infections in mental health services should be included in the recommendations that may reduce BO and STS among MHWs.