Within the area of cancer care, mindfulness-based therapeutic interventions have been found to be efficacious in reducing psychological distress related to a cancer diagnosis; however, the impact of mindfulness-based interventions on quality of life is unclear. This study explores the impact of a Mindfulness-Based Cancer Stress Management programme on psychological distress and quality of life. Research methodology included a single-group quasi-experimental study of 26 participants experiencing distress related to a cancer diagnosis, including carers, who completed an MBCSM programme and all assessments. Participants completed the Functional Assessment of Cancer Therapy - General version 4 (FACT-G) and its associated spirituality index (FACIT-Sp-Ex), Hospital Anxiety and Depression Scale (HADS), Freiburg Mindfulness Inventory (FMI), and the Distress Thermometer at baseline, post-intervention, and three months after programme completion. Significant improvements were observed on all measures (ranges: P ≤ 0.001 to 0.008, r = -0.53 to -0.79) following the intervention, which were maintained at 3-month follow-up. Mindfulness was significantly correlated with all main outcome measures at post-intervention (range: r = -0.41 to 0.67) and 3-month follow-up (range: r = -0.49 to 0.73), providing evidence for the internal validity of the study. Our findings indicate that the MBCSM programme is effective in reducing psychological distress and improving quality of life, including spiritual well-being.