PurposeMen diagnosed with advanced prostate cancer experience higher psychological distress and greater unmet supportive care needs than men with localized disease. A mindfulness-based cognitive therapy group intervention was pilot tested for acceptability and effectiveness in this patient group. Methods Nineteen men were initially recruited to three groups and 12 completed final assessments. Outcomes assessed included anxiety, depression, cancer-related distress, prostate cancer-specific quality of life, and mindfulness skills at baseline, immediately, and 3 months post-intervention. Satisfaction measures and in-depth interviews were undertaken post-intervention to describe men's personal experiences of the groups. Results Significant improvements were observed for anxiety (p = 0.027), avoidance (p = 0.032), and mindfulness skills (p = 0.019), with a trend for a reduction in fear of cancer recurrence (p = 0.062). Effect sizes were moderate to large. A shared group identity, acceptance of, and learning from other group members were key aspects of the group context that contributed to acceptance of progressive disease. Conclusions Mindfulness-based group interventions appear to have utility in this patient group and show promise for reducing anxiety, avoidance, and fear of cancer recurrence. Peer learning appeared to be helpful in generating acceptance of advancing disease.