Objectives: Smoking remains a major modifiable health risk among older adults. However, limited research has explored how lifelong occupational experiences influence smoking behavior in this population. This study examined the association between longest-held occupation and current smoking among older adults in South Korea. Methods: We analyzed data from 9,920 individuals aged 65 and above who participated in the 2020 National Survey of Older Koreans. Multivariable binary logistic regression was performed using SAS 9.4, with analyses stratified by gender. Results: Among older men, those classified as “blue-collar & wage and salary workers” had significantly higher odds of smoking compared to their “white-collar & wage and salary” counterparts. By contrast, lifelong non-economically active individuals had lower odds of smoking. No significant associations were observed among older women. Conclusion: Longest-held occupation is a significant predictor of smoking behavior among older men, underscoring the need for gender-specific and occupation-informed interventions. Integrating lifetime occupational history into health behavior research and policy concerning older adults may be particularly valuable for improving smoking cessation strategies in high-risk subgroups.