Aim Poor oral status is associated with increased physical dependency and cognitive decline. Malnutrition, a potential result of poor oral status, is associated with poorer rehabilitation outcome and physical function. However, the association between oral status and rehabilitation outcome is not fully understood. The present study investigated the association of poor oral status with rehabilitation outcome in older patients. Methods A retrospective cohort study was carried out of 108 consecutive patients (mean age 80.5 ± 6.8 years; 50.9% men) who were admitted to convalescent rehabilitation wards. The Revised Oral Assessment Guide was used to evaluate oral status. Rehabilitation outcome was evaluated by the Functional Independence Measure (FIM) on discharge. Multivariate analyses were applied to examine the associations between poor oral status and motor‐FIM on discharge. Results According to the Revised Oral Assessment Guide score, 14.8% of participants had normal oral status, 52.8% had slight to moderate oral problems and 32.4% had severe oral problems. The median scores of motor‐FIM on admission and on discharge were 52 (interquartile range 25–70) and 75 (interquartile range 51–89), respectively. Multivariate analysis showed that the Revised Oral Assessment Guide score and the motor‐/cognitive‐FIM scores on admission were significant independent factors for motor‐FIM on discharge, after adjusted for sex, age, length of stay, nutritional status, handgrip and causative diseases (P < 0.001). Conclusions Poor oral status is associated with rehabilitation outcome in older people. Geriatr Gerontol Int 2017; 17: 598–604.