Aims and Objectives To explore the association between patient and caregiver depression and patient self‐care and caregiver contribution to self‐care in the context of ostomy care. Background Self‐care is essential for ostomy patients and their caregivers. The ostomy self‐care process can be considered a dyadic phenomenon in which the patient and the caregiver interact together and work as a team. The presence of depressive symptoms may limit the patient's ability to perform self‐care and caregivers' abilities to engage in caregiving tasks. Research into the dyadic influence of depression on self‐care behaviours from the perspective of ostomates and their caregivers is still in its infancy. Design Secondary analysis of a multicentre, cross‐sectional study. The STROBE checklist was used to report the present study. Methods Patient–caregiver dyads were recruited from eight ostomy outpatient clinics from February 2017 to May 2018. Depression was assessed with the nine‐item Patient Health Questionnaire in both patients and caregivers. Patient self‐care was evaluated with the Ostomy Self‐Care Index, and caregiver contribution to self‐care was assessed with the Caregiver Contribution to Ostomy Self‐Care Index. Both instruments measure the dimensions of maintenance, monitoring and management. The actor–partner interdependence model was performed for the dyadic analysis. Results In total, 252 patient–caregiver dyads (patients: 69.8% male, mean age 70.05; caregivers: 80.6% female, mean age 58.7) were enrolled. Patient depression was positively associated with caregiver contribution to self‐care maintenance. Caregiver depression was negatively associated with self‐care management. Relevance to Clinical Practice These findings add a better understanding of the reciprocal influence of dyadic depression on patient and caregiver contributions to self‐care in ostomy contexts was found. Patient and caregiver depression influence patient self‐care and caregiver contribution to self‐care. Therefore, clinicians should assess and treat depression in both members of the dyad to improve self‐care.