To evaluate the relationship between social isolation, loneliness and psychological well-being in patients with inflammatory bowel disease (IBD). Additionally, we examined the mediating effect of disease activity on the relationships between social isolation, loneliness and psychological well-being. Cross-sectional descriptive study. A total of 218 participants were recruited from outpatient clinic at a university hospital in Turkey and from the community membership of the patient support group. Participants provided their socio-demographic and disease-related information and completed (online and paper based) the Turkish Lubben Social Network Scale-6, the Turkish UCLA Loneliness Scale Short Form and the Turkish Psychological Well-being Scale. The data were analysed using univariate linear regression analysis. This study adhered to the STROBE checklist for reporting. The majority of the participants (72%) were socially isolated, and over half (54.1%) reported moderate to high levels of loneliness. Participants also had low psychological well-being. Linear regression analysis revealed that high loneliness level and social isolation were negative predictors of psychological well-being. The results revealed that the effect of social isolation and loneliness on psychological well-being was mediated by disease activity. In line with the findings, it can be recommended to enhance social support and networks, along with regular psychological evaluation, should be integrated into the holistic care approach for IBD patients. The findings of this study hold significant implications for the management and support of patients with IBD, particularly within clinical settings in Turkey. Patients were invited to complete questionnaires. The investigators explained the study's content and purpose, and addressed any concerns during the data collection process.