<p>Recent studies have increasingly focused on the complex relationship between social support and mental health, though consensus on their interactions remains elusive. This study, based on a survey of 439 individuals from the border region of Yunnan Province, China, examines the impact of social support on the mental health of border dwellers and the mechanisms underlying this relationship. Our findings indicate that social support positively influences the mental health of border dwellers. Additionally, psychological capital and meaning in life partially mediate this relationship. Specifically, both factors serve as independent mediators, with psychological capital and meaning in life also acting as sequential mediators between social support and mental health. Rooted in Western social support theory but framed within a Chinese cultural context, this research provides valuable insights for improving the mental well-being of border dwellers in Southwest China.</p>