This study aimed to explore factors associated with proactive health knowledge, attitude, and practice among older adults. A questionnaire survey was conducted among 465 older adults using purposive sampling. Binary logistic regression and Shapley value decomposition were employed to analyze the related factors and their contributions to proactive health knowledge, attitude, and practice levels. Regression analysis showed that increasing age, alcohol consumption, and undergoing chronic disease re-examination once a year were risk factors for knowledge levels, while higher income and better access to medical institutions were protective factors for knowledge levels. Higher income and sleep duration had positive and negative effects, respectively, on attitude. Alcohol consumption was a risk factor for proactive health behavior, whereas digital health literacy and a higher frequency of chronic disease re-examinations were protective factors for behavior. Social support was identified as a common positive factor across knowledge, attitude, and practice. Shapley value decomposition further revealed that social support consistently ranked among the top contributors across all three dimensions of proactive health knowledge, attitude, and practice, serving as a core factor. Individual-level factors, including educational attainment, annual personal income, and sleep duration, also demonstrated considerable explanatory power. The study suggests that sustainable community support networks should be established and integrated with digital skills training. Lifestyle health education should be tailored to differences in educational attainment. The accessibility and continuity of primary healthcare services should be optimized, and proactive health guidance should be embedded into chronic disease follow-up procedures.