This study aimed to investigate the association between sanitary toilets and health poverty vulnerability among rural western Chinese adults aged 45 years and older. Using data from the ’Rural Household Health Inquiry Survey’ conducted in 2022, a three-stage feasible generalized least squares method was employed to calculate health poverty vulnerability. Propensity score matching (PSM) and mediation effect analysis were used to assess the association between sanitary toilets and health poverty vulnerability among rural western Chinese adults aged 45 years and older and the mechanisms underlying this impact. This study revealed that the use of sanitary toilets was significantly associated with decreased health poverty vulnerability in adults over 45 years of age. Heterogeneity analysis revealed that this effect was more pronounced among males (β = -0.0375, P<0.05), those aged 60–74 years (β = -0.0476, P<0.05), and households with middle income (β = -0.0590, P<0.01). Mediation effect analysis identified total household income (a×b = -0.0233, P<0.05), household size (a×b = -0.0181, P<0.01), number of household laborers (a×b = -0.0107, P<0.01), and registered poor households (a×b = -0.0081, P<0.01) as the mediating factors between sanitary toilets and health poverty vulnerability. The provision of sanitary toilets has been instrumental in mitigating health-related poverty among middle-aged and elderly people residing in rural areas. By improving household livelihood capital, the vulnerability of these individuals to health-related poverty can be significantly reduced.