Background: Family doctor contract services are essential to primary healthcare, significantly improving older adults’ health. However, contract rates among older individuals are various. Investigating factors influencing these rates is crucial for optimizing policies and enhancing contract rates. Methods: This study used 2018 data from Wangying Community Health Service Center, encompassing 8,625 older adults. Propensity score matching (PSM) was applied to balance potential confounders between those with and without contracts. Multiple logistic regression analysis explored the effects of gender, age, the number of medical visits, and the number of chronic diseases on contracting behavior. Results: Gender did not significantly impact contracting behavior. However, age, the number of medical visits, and the number of chronic diseases significantly influenced it ( β = 0.457, p < 0.01; β = 0.286, p < 0.05; β = -0.229, p < 0.1). An inverted U-shaped relationship was found between age and contracting behavior ( β = -0.003, p < 0.01). Conclusion: Age, the number of medical visits, and number of chronic diseases are key factors in family doctor contracting behavior among older adults. Enhanced policy support is needed to promote contract signing, improving health security for older individuals.