This study examined concordances of cancer patients' received and caregivers' provided support and dyadic relationship quality, and their predictive utility in prospective psychological distress and well-being. A total of 83 Chinese cancer patient-caregiver dyads were recruited in two government-funded hospitals in Hong Kong. Participants reported received (patient)/provided (caregiver) emotional and instrumental support and dyadic relationship quality within 6 months after diagnosis (T1), and anxiety and depressive symptoms, positive affect and life satisfaction at both T1 and 6-month follow-up (T2). We hypothesised that concordances at T1 would predict lower psychological distress and higher psychological well-being among both patients and caregivers at T2. Concordances were indicated by Gwet's AC scores (possible range = -1.00 to 1.00) and as follows: emotional support: M = 0.92, SD = 0.12, range = 0.25-1.00; instrumental support: M = 0.92, SD = 0.16, range = 0.08-1.00; and relationship quality: M = 0.63, SD = 0.27, range = -0.31 to 1.00. Hierarchical multiple regressions revealed that T1 concordances of perceived emotional and instrumental support and dyadic relationship quality positively predicted T2 anxiety symptoms [F(9, 74) = 6.725, ∆R = .031, p < .001)] and state positive affect [F(9, 74) = 3.436, ∆R = .042, p = .001)], whereas inversely predicted T2 depressive symptoms [F(9, 74) = 4.189, ∆R = .042, p < .01)]. Significant associations were found only among caregivers, but not patients.