Mandala drawing was first practiced by Tibetan buddhists and then developed by Carl Gustav Jung, who felt certain that mandala drawing has the function of integrating psychological division, enhancing psychological harmony, and preserving personality integrity. Previous studies on mandala drawing have mainly focused on alleviating people’s negative emotions, such as anxiety and depression. Therefore, this study explored the effect and mechanism of mandala drawing on the improvement of subjective well-being (SWB), mindfulness, and spirituality from positive psychology’s viewpoint and compared the different effects of cooperative mandala drawing (CMD) and individual mandala drawing (IMD) on mindfulness, spirituality, and SWB. A total of 76 students were recruited from Chang Gung University, and the aforementioned three main variables were measured before and after the coloring experiment. The results indicated that both CMD and IMD significantly enhanced the subjects’ spirituality. Compared with IMD, CMD has a more significant improvement and promotion effect on SWB of subjects by affecting PA, while IMD had no significant effect on PA, and the enhancement effect of SWB was weaker than that of CMD. Mindfulness, spirituality, and SWB all positively correlated with each other. This study highlights the mechanism of mandala drawing and the theoretical understanding of the relationship between mindfulness and SWB. Mandala drawing especially CMD has a positive effect on spirituality and SWB, which may provide individuals with a simple and easy method to improve their happiness.