Over the last decades, music therapy (MT) and music-based interventions have gained increasing recognition in psychiatry. Music exerts beneficial effects on both the psychological and physiological states associated with mental disorders. This chapter summarizes the applications of MT and music-based interventions across a broad spectrum of psychiatric disorders, such as depression, schizophrenia, anxiety, obsessive-compulsive disorder, post-traumatic stress disorder, sleep disorders, substance use disorders, and eating disorders. After summarizing the key characteristics of each condition, we illustrate the mechanisms underlying the potential efficacy of music and conclude with a presentation of the main literature findings about the effects of MT and music-based interventions. Overall, the literature suggests that music may represent a promising viable, free-of-cost, therapeutic tool in psychiatry. MT and music-based interventions should be considered as complementary treatment strategies by professionals in the field of mental health. Future studies with methodologically sound designs and larger samples are needed to evaluate the efficacy and tolerability of MT and music-based interventions in understudied mental disorders, focusing specifically on the long-term efficacy and the lasting effects after discontinuation.