Abstract The aim of the present study was to assess the relationship between sitting balance at an early stage and activities of daily living (ADL) function in 452 stroke patients. The effect of sitting balance on the two core elements of depression (apathy and depressive mood) was also examined. The ability to maintain a sitting position for 10 min (10-min sitting balance) was assessed, along with ADL using the Functional Independence Measurement, and psychological status using the Zung Self-rating Depression Scale (depressive mood), Apathy Scale (apathy) and Neuropsychiatric Inventory. Proportional-hazards analysis was used to determine the independent effect of post-stroke depression on functional outcome. Comparisons between sitting balance and psychological status were performed using logistic multiple regression analysis. Cox multiple regression analysis showed that significant differences were obtained for the sitting balance (P < 0.0002) and Mini-Mental State Examination scores (P < 0.02) in all six ADL subscales, and for age in four of the six ADL subscales (Dressing–Upper Body and Dressing–Lower Body, Toileting, Walking). Kaplan–Meier survival curves for reaching independence in ADL subscales showed highly significantly differences in achievement rate and time to reach goal for each subgroup on 10-min sitting balance (with or without assistance) and on age (young, <65; elderly, ≥65 years). Ten-minute sitting balance correlated with depressive mood and apathy. A rapid and simple screening method, 10-min sitting balance was related to scores for two core depressive symptoms, lowered mood and apathy, and was predictive of post-stroke ADL outcomes in the rehabilitation unit along with age.