Cancer patients may experience psychological distress, like anxiety and depressive symptoms. Mindfulness-based cognitive therapy (MBCT) has been shown to alleviate this psychological distress. However, patients experience barriers in participating in face-to-face MBCT. Individual internet-based MBCT (eMBCT) could be an alternative.<br/> AIM: To compare MBCT and eMBCT to treatment as usual (TAU) for psychological distress in cancer patients.<br/> METHOD: 245 cancer patients with psychological distress were randomly allocated to MBCT (n = 77), eMBCT (n = 90) or TAU (n = 78). Patients completed baseline (T0) and post-intervention (T1) assessments. The primary outcome was psychological distress on the Hospital Anxiety and Depression Scale. Outcomes were analyzed using linear mixed modeling on the intention-to-treat sample. Since both interventions were compared to TAU, the type I error rate was set to p < 0.025.<br/> RESULTS: Compared to TAU, patients reported significantly less psychological distress after both MBCT (Cohen's d = 0.43, p < 0.001) and eMBCT (Cohen's d = 0.63, p < 0.001).<br/> CONCLUSION: Compared to TAU, MBCT and eMBCT were similarly effective in reducing psychological distress in a sample of distressed heterogeneous cancer patients.