Objectives: This study aimed to investigate the associations between the number of natural teeth, masticatory discomfort, and life functioning in older adults. Methods: Data from the 2024 Korea National Health and Nutrition Examination Survey were used. A total of 1,429 subjects aged 65 years or older were included. A complex sample linear regression analysis was conducted to examine the associations between the number of natural teeth, masticatory discomfort, and life functioning. The Life Functioning Scale-10 (LF-10) was used to assess life functioning in older adults. Results: The LF-10 score was significantly lower in subjects with 19 or fewer natural teeth (82.23) than in those with 20 or more natural teeth (88.72). It was also significantly lower in subjects with masticatory discomfort (78.89) than in those without masticatory discomfort (88.83). After adjusting for confounding variables, subjects with 19 or fewer natural teeth and those with masticatory discomfort had significantly lower LF-10 scores by 2.819 and 6.155 points, respectively. Conclusions: The results of this study suggest that the number of natural teeth and masticatory discomfort are associated with LF-10 scores, a measure of life functioning in older adults.