This study examines the impact of community choir participation on adult well-being among Shenzhen residents, a city with a diverse immigrant population and rapid growth. Using an embedded mixed-methods design for 6 months, 90 participants (aged 25-45, no prior choral experience) were divided into Group A (music appreciation) and Group B (choir rehearsals after 1 month). Quantitative data from the well-being (Quality of Life scale) survey and qualitative interviews revealed significant improvements in Group B across six dimensions: material well-being, relationships, social activities, personal development, recreation, and independence. Group B participants, including many with no musical background, showed greater potential for growth, driven by anticipation, belonging, and mentorship. This study advocates for integrating community choirs into public health initiatives and emphasizes their role in enhancing urban adults' well-being, social connections, and personal growth. It encourages more musical novices to join choirs and urges music educators to actively support adults in overcoming fears of participation due to lack of musical knowledge, contributing to broader frameworks for arts-based social transformation.