OBJECTIVES: Fatigue is prevalent in patients with inflammatory bowel disease (IBD) in remission. Previously, we showed that fatigued IBD patients experienced a significant decrease in fatigue after receiving mindfulness-based cognitive therapy (MBCT). The current study examined to what extent these short-term beneficial effects of MBCT on fatigue were maintained over nine months follow-up, and whether patient characteristics were associated with clinically relevant improvement in fatigue. METHODS: A randomized controlled trial, including an MBCT and waiting-list control condition, was performed in fatigued IBD patients in remission. For this study, we analysed long-term outcomes of 108 patients who received MBCT (either directly or after three months waiting). The primary outcome was fatigue, assessed with the Checklist Individual Strenght-20. Secondary outcomes included fatigue interference, depression, anxiety, and quality of life. RESULTS: The reduced level of fatigue post-treatment did not change significantly during follow-up (F(2,76) = 1.68, p = 0.19). In total, 29% of patients reported clinically relevant improvement from pre-treatment to nine months follow-up. We found few significant differences in baseline characteristics between those reporting clinically relevant improvement and those not, except that patients who improved were significantly more often unemployed (χ2(1, n = 73) = 4.40, p = 0.04). Secondary outcomes, which did not change significantly during MBCT, also remained stable during follow-up. CONCLUSION: Findings suggest that reductions in IBD-related fatigue after receiving MBCT are sustained over nine months follow-up, with around one-third of patients reporting clinically relevant improvement from pre-treatment to follow-up. Employment status might be related to improvements in fatigue. Future research is needed to confirm these long-term outcomes. PREREGISTRATION: ClinicalTrials.gov ID: NCT03162575.