BackgroundWe aimed to demonstrate the associations between social interactions within social distancing norms during the coronavirus disease 2019 (COVID-19) pandemic and cognitive function among South Korean older adults.MethodsData from the 2017 and 2020 Survey of Living Conditions and Welfare Needs of Korean Older Persons were used. There were 18,813 participants (7,539 males; 11,274 females). T-test and multiple logistic regression analyses verified whether the mean difference in older adults’ cognitive function before and during the COVID-19 pandemic was statistically significant. We also examined the associations between social interactions and cognitive function. The key results were presented as odds ratios (ORs) and 95% confidence intervals (CI).ResultsAll participants were more likely to experience cognitive impairment during the COVID-19 pandemic than before (males: OR 1.56, 95% CI 1.3–1.78; females: OR 1.26, 95% CI: 1.14–1.40). Cognitive impairment increased linearly with the decreased frequency of face-to-face contact with non-cohabiting children. Possible cognitive impairment was greater for females who had not visited senior welfare centers for the past year (OR 1.43, 95% CI 1.21–1.69).ConclusionKorean older adults’ cognitive function declined during the COVID-19 pandemic and was associated with reduced social interactions because of social distancing measures. Alternative interventions should be promoted for safely restoring social networks, considering the adverse effects of long-term social distancing on older adults’ mental health and cognitive function.