This chapter presents a study that investigated how multilingualism shapes university students’ psychological well-being and the design of mental-health support in two highly internationalized yet culturally distinctive global higher-education hubs, Hong Kong and Singapore. We advance an integrated framework spanning (i) language-related stressors, (ii) acculturation pathways, and (iii) institutional mechanisms, and apply it in a comparative case study combining documentary analysis and semi-structured interviews. We show that language hierarchies and frequent code-switching intersect with identity and stigma to condition help-seeking and campus belonging, while institutional designs can either mitigate or reproduce these pressures. Focusing on Mainland Chinese students, the largest non-local cohort in both systems, we trace how linguistic repertoire, cultural expectations, and service accessibility jointly shape psychological adjustment and academic integration. The chapter contributes a theoretically grounded, practice-oriented lens for multilingual mental-health education and concludes with targeted recommendations on linguistically accessible counselling, culturally sensitive pedagogy, and hybrid integration programs to better support Mainland Chinese students’ well-being in Hong Kong and Singapore.