BACKGROUND: Coeliac disease is a chronic gastrointestinal condition associated with an increased risk of psychiatric comorbidity, and diminished quality of life. Ongoing gastrointestinal symptomatology is frequently reported post-diagnosis, despite undertaking a gluten-free diet. PURPOSE: To examine the role of psychosocial factors in mediating the relationship between gastrointestinal symptoms and quality of life, using a cross-sectional structural equation modelling mediation analysis guided by the Common-Sense Model. METHODS: 1697 adults with coeliac disease (83.1% female, mean age = 55.79, SD = 14.98 years) completed an online questionnaire. Measures included gluten-free diet adherence, gastrointestinal symptoms, illness perceptions, coping, gastrointestinal-specific anxiety, pain catastrophising, psychological flexibility, psychological distress, and quality of life. RESULTS: A structural equation model was developed explaining 50.6% of the variation in quality of life and demonstrating good fit (χ2 (2) = 8.54, p = .014, χ2/N = 4.27, RMSEA = 0.04, SRMR = 0.01, CFI = 0.999, TLI = 0.98, GFI = 0.999). Gastrointestinal symptoms directly affected quality of life, and indirectly, via negative illness perceptions, maladaptive coping, pain catastrophising, and psychological distress. CONCLUSION: Psychosocial processes may affect adjustment in coeliac disease by mediating the relationship between gastrointestinal symptoms and quality of life. Individuals living with coeliac disease may benefit from interventions targeting maladaptive psychosocial factors.