Aim To examine the longitudinal association between dentition status and incidence of frailty in older adults. Methods The present prospective cohort study included community‐dwelling Japanese adults aged 75 years at baseline (n = 322). Dental examinations, biochemical blood examinations, physical performance and anthropometric measurements, and structured questionnaires were carried out at baseline. The presence of ≥20 teeth with nine or more occluding pairs of teeth was defined as functional dentition. Annual follow‐up examinations, including physical performance, anthropometric measurements and structured questionnaires, were carried out over a 5‐year period to determine the incidence of frailty, defined as three or more of the following five components derived from the Cardiovascular Health Study: weight loss, weakness, slowness, poor energy and low physical activity level. Adjusted hazard ratios of frailty incidence according to dentition status were calculated from Cox proportional hazards regression analyses. Results At baseline, 118 participants (36.6%) were defined as having functional dentition. During the follow up, 48 participants (14.9%) developed frailty. The adjusted hazard ratio for frailty in participants with functional dentition was 0.50 (95% confidence interval 0.25–0.98) compared with participants without functional dentition, after adjusting for sex, income, education, smoking status, body mass index, serum biomarkers and comorbidities. Conclusions Functional dentition was significantly associated with a lower risk of frailty defined by the Cardiovascular Health Study frailty index in older Japanese adults. These results suggest that maintaining healthy and functional dentition into later life is important for frailty prevention. Geriatr Gerontol Int 2017; ••: ••–••.