This study aims to test which factors influence and aid the psychosocial adjustment of patients with an ostomy and to provide data for the development of programmes for the self‐management of and psychosocial adjustment to intestinal stomas. A total of 150 ostomy patients were recruited between December 1, 2017 and March 26, 2018 in Korea and completed self‐report questionnaires. Data of 25 participants were excluded, resulting in a sample size of 125 participants. Factors, including social support subtypes and self‐efficacy, that influence the psychosocial adjustment were analysed using Cox's regression. Of the factors that influenced the adjustment groups after adjusting for time, the following subtypes of social support were found to influence the patients' adjustment: the patients' psychosocial adjustment increased by 0.4 when the level of medical staff support increased by 1 (Exp[B] = 1.04, P = 0.007), and adjustment decreased by 0.3 when the level of family support increased by 1 (Exp[B] = 0.97, P < 0.001). As medical staff support who have expertise exert more of an influence on the psychosocial adjustment of ostomy patients than self‐efficacy and family support, psychosocial adjustment programmes that reflect this and nurses specialised in care for ostomy patients are required.