The psychological effects of the COVID-19 pandemic on the Portuguese population are quite relevant and partially related to their repetitive and disruptive thinking about the disease. The successive periods of lockdown contributed to an additional burden on the family–work–life balance for parents. This study aims to validate the Portuguese version of the Obsession with COVID-19 Scale (PT-OCS), which was developed using a general sample from several regions of the country (n = 531) together with a specific sample of Portuguese parents (n = 109). The confirmatory factor analysis results indicate that the PT-OCS includes a set of excellent psychometric properties concerning both the general sample (χ2(1) = 0.446, p = 0.504; CFI = 1.0; GFI = 1.0; RMSEA = 0.0; standardised RMR = 0.003) and the parent group (χ2(2) = 1.816, p = 0.403; CFI = 1.0; GFI = 0.99; RMSEA = 0.0; standardised RMR = 0.016; Bollen–Stine bootstrap p = 0.65). The scale shows very good reliability (0.84 < α/ω < 0.88). As expected, obsession with COVID-19 was highly correlated with COVID-19 anxiety, and women had higher PT-OCS scores. The findings suggest that the PT-OCS is a reliable and valid measure for both persistent and disruptive thinking about COVID-19 in different groups of the Portuguese population, with potential for studying future epidemic events.