The present study examined whether geographic location (i.e., rural vs. urban areas) moderated the relationship between social capital and COVID-19 preventive behaviors among older adults in South Korea. Participants were a nationally representative sample of 61 075 Korean adults aged 65 years or older from the 2021 Community Health Survey by the Korea Disease Control and Prevention Agency. The moderation analysis was conducted with PROCESS. After adjusting for covariates, the moderation analysis showed a significant moderation effect of geographic location on the relationship between social capital and COVID-19 preventive behaviors among older adults in South Korea. Specifically, in urban areas, older adults with higher social capital were more likely to adhere to COVID-19 preventive behaviors. However, social capital negatively impacted older adults' COVID-19 preventive behaviors in rural areas. Findings suggest that social capital is not always helpful for maintaining COVID-19 preventive behaviors among older adults in South Korea. The social characteristics of geographic location need to be considered when initiating COVID-19 prevention campaigns in South Korea. Geriatr Gerontol Int 2024; 24: 377-384.