Introduction The potential for bacillus Calmette–Guérin (BCG) vaccination to mitigate coronavirus disease 2019 (COVID-19) severity and perhaps infection susceptibility has been hypothesized, attracting global attention given its off-target benefits demonstrated in several respiratory viral infections. Methods In this retrospective study, patients with laboratory-confirmed COVID-19 from Wuhan Pulmonary Hospital, China were categorized into BCG vaccination and non-vaccination groups. Clinical records, demography, laboratory results, and chest computed tomography scans were extracted from electronic medical records and compared between the 2 groups. Results No adverse events were observed, except for an increased frequency of chills in the BCG-vaccinated group versus the unvaccinated group ( p =0.014). There were no significant differences in oxygen demand for breathing, computed tomography scans, treatments, or outcomes between the 2 groups. However, BCG vaccination was associated with significantly less severe pneumonia ( p =0.028) and milder deficiency in liver function, consistent with a lower death rate in comparison with the unvaccinated group. Conclusions BCG vaccination received in childhood is associated with less severe COVID-19 pneumonia and milder liver function deficiency in addition to a lower death rate in BCG-vaccinated patients versus non-vaccinated individuals.