Cancer has different psychological and physical outcomes. The present study was conducted to examine psychological distress, posttraumatic growth, and dispositional mindfulness in cancer patients. A total of 109 cancer patients entered the research. The Five-Facet Mindfulness Questionnaire (FFMQ), the Depression Anxiety Stress Scales (DASS-21), and the Posttraumatic Growth Inventory (PTGI) were used for data collection. The regression analysis revealed that dispositional mindfulness can be a significant predictor of psychological distress and posttraumatic growth in cancer patients. The results also showed that mindfulness is related significantly to psychological outcomes and adaptation in cancer patients and should be further addressed in cancer treatment.