Abstract Background The relationship of bidirectional sharing of information between physicians and patients to patient satisfaction with treatment decision-making for ulcerative colitis (UC) has not been examined. Here, we conducted a web-based survey to evaluate this relationship. Methods Patients aged ≥ 20 years with UC were recruited from the IBD Patient Panel and Japanese IBD Patient Association. Patients completed our web-based survey between 11 May and 1 June 2020. The main outcomes were patient satisfaction (assessed by the Decision Regret Scale) and patient trust in physicians (assessed by the Trust in Physician Scale). Results In this study (n = 457), a structural equation modelling analysis showed that physician-to-patient and patient-to-physician information significantly affected patient satisfaction with treatment decision-making (standardised path coefficient: 0.426 and 0.135, respectively) and patient trust in physicians (0.587 and 0.158, respectively). Notably, physician-to-patient information had a greater impact. For patient satisfaction with treatment decision-making and patient trust in physicians, information on “disease” (indirect effect: 0.342 and 0.471, respectively), “treatment” (0.335 and 0.461, respectively), and “endoscopy” (0.295 and 0.407, respectively) was particularly important, and the level of this information was adequate or almost adequate. Patient-to-physician information on “anxiety and distress” (0.116 and 0.136, respectively), “intention and desire for treatment” (0.113 and 0.132, respectively), and “future expectations of life” (0.104 and 0.121, respectively) were also important for patient satisfaction with treatment decision-making and patient trust in physicians, but these concerns were not adequately communicated. Conclusions Adequate physician–patient communication, especially physician-to-patient information, enhanced patient satisfaction with treatment decision-making for UC.