This paper explores the emergence of painting art therapy as a major breakthrough in humanistic medicine, and its use as a clinical adjunct to treat various diseases. Through a literature review, the paper reveals that the healing mechanisms of painting art therapy are based on a combination of factors, including the Mind-Body Connectivity theory and brain plasticity. The therapy is effective due to the immersion in the present moment in a mindfulness way, non-verbal and symbolic forms that facilitate free expression and reconstruction, and a high-quality therapeutic relationship. The widespread use of painting art therapy proves its universality and effectiveness, highlighting the importance of humanities in medical settings.