BACKGROUND The Decade of Healthy Aging 2021-2030 calls for a strengthening of the policies for older people in Latin America. An example of successful oral aging is the Japanese "8020" campaign, which achieved 50% of people aged 80 years having ≥20 teeth by 2016. OBJECTIVE To evaluate the association between having a functional dentition (≥20 teeth) and cognitive health, social participation, and quality of life in people aged ≥80 years. METHODS Cross-sectional data from 299 complete observations (weighted N = 436 981) of individuals aged ≥80 years from Chile's National Health Survey 2016-2017 were included (3% of the population; total = 5520 clinical observations/weighted N = 14 518 969). Generalised structural equation models (GSEM) evaluated the association between having a functional dentition and cognitive health, measured with the Mini-mental score, between having a functional dentition and social participation, and between having a functional dentition and quality of life, measured with the EQ-5D-3L. Models included the effect of mediators (daily fruit and vegetable consumption; oral health-related quality of life score) and controlled for the exposure-induced mediator-outcome variables: sex, educational level, and location. Data were analysed using the STATA-17 survey module. Statistical significance was set at P < .05 (95% confidence interval [CI]). RESULTS The sample was mostly female, had <8 years of education, and lived in urban areas. The prevalence of a functional dentition was 9.2% (95% CI 3.6,21.3/n = 21). GSEM demonstrated that the association between functional dentition and cognitive health was mediated by daily fruits and vegetables consumption (β = 0.12/95% CI 0.02,0.21/P = .015), with moderate strength of evidence. Additionally, there was strong evidence of an association between functional dentition and social participation frequency (β = 2.76/95% CI 0.60,4.73/P = .009). Finally, the association between functional dentition and quality of life was mediated by cognitive health (β =0.05/95% CI 0.02,0.09/P = .002) and oral health-related quality of life (β = -0.04/95% CI -0.08 to -0.01/P = .025), with strong and moderate evidence, respectively. CONCLUSIONS Given the beneficial implications of functional dentition in social participation, nutritional benefits and quality of life and well-being of individuals aged ≥80 years.