Background: We aimed to examine the impacts of digital healthy diet literacy (DDL) and healthy eating behaviors (HES) on fear of COVID-19, changes in mental health, and health-related quality of life (HRQoL) among front-line healthcare workers (HCWs). Methods: An online survey was conducted at 15 hospitals and health centers from 6–19 April 2020. Data of 2299 front-line HCWs were analyzed—including socio-demographics, symptoms like COVID-19, health literacy, eHealth literacy, DDL, HES, fear of COVID-19, changes in mental health, and HRQoL. Regression models were used to examine the associations. Results: HCWs with higher scores of DDL and HES had lower scores of FCoV-19S (regression coefficient, B, −0.04; 95% confidence interval, 95%CI, −0.07, −0.02; p = 0.001; and B, −0.10; 95%CI, −0.15, −0.06; p < 0.001); had a higher likelihood of stable or better mental health status (odds ratio, OR, 1.02; 95%CI, 1.00, 1.05; p = 0.029; and OR, 1.04; 95%CI, 1.00, 1.07; p = 0.043); and HRQoL (OR, 1.02; 95%CI, 1.01, 1.03; p = 0.006; and OR, 1.04; 95%CI, 1.02, 1.06; p = 0.001), respectively. Conclusions: DDL and HES were found as independent predictors of fear of COVID−19, changes in mental health status, and HRQoL in front-line HCWs. Improving DDL and HES should be considered as a strategic approach for hospitals and healthcare systems.