Objectives: We analyzed factors impacting health-related quality of life (HRQoL) among Korean older adults, as measured by the EuroQol 5 Dimensions (EQ-5D), and compared trends over time. Methods: Data were obtained from the Korea National Health and Nutrition Examination Survey (KNHANES). Using data collected every four years from 2016 to 2024, we examined factors associated with older adults’ quality of life during each survey period. Participants were aged 65 years or older, with a sample size of 1,578 in 2016, 1,681 in 2020, and 1,951 in 2024. Complex sample logistic regression was used for statistical analyses. Results: Spanning the survey periods, sex and activity limitations consistently emerged as significant determinants of HRQoL. In 2016 and 2024, economic activity, stress, and unmet dental care were also significant factors, whereas in 2020, smoking and chewing discomfort were significant. Conclusions: HRQoL in older adults is influenced by interactions between structural factors (sex and activity limitations) and environmental and behavioral factors (economic activity, mental health, and oral health). Issues related to dental care access, such as unmet dental treatment needs, exert long-term impacts on quality of life, underscoring the need for integrated elderly health policies and early interventions to support health management.