<p>Air pollution has been linked to an increased risk of cardiometabolic diseases (CMDs) among middle-aged and elderly individuals. However, few large-scale empirical studies have tested this correlations base on Chinese samples, and research on the urban–rural differences remains limited. This study aims to explore the relationship between air pollution (specifically PM2.5) and the risk of CMDs in middle-aged and elderly individuals, examining urban–rural inequality and assessing the moderating effect of healthcare resources. Data from the fourth wave of the China Health and Retirement Longitudinal Study (CHARLS), combined with a high-resolution PM2.5 dataset and data on practicing physicians from local Chinese governments, were used. A logistic regression model was employed to analyze disease-specific risks, assess urban–rural heterogeneity, and test moderating effects. Robustness analysis was performed to enhance the reliability of the findings. The results showed that PM2.5 exposure is significant correlated with five CMDs: hypertension, diabetes, dyslipidemia, heart disease, and stroke. The impact posed by PM2.5 differed between urban and rural areas that rural residents showed more vulnerable to air pollution. Increasing practicing physicians was found to mitigate the impact of PM2.5 on CMDs in the targeted people, especially for rural residents. The study suggests that local government should pay more attention towards the health of rural residents rather than urban residents, and implementing differentiated prevention and control measures. The allocation of medical resources should be continuously optimized, with a focus on increasing practicing physicians, particularly in rural areas, to strengthen health protection capabilities. Developing a comprehensive urban–rural integrated medical service system will be crucial in elevating the standard of medical services in rural regions.</p>