Identifying modifiable correlates of older adults' preventive behaviors is contributable to the prevention of the COVID-19 and future pandemics. This study aimed to examine the associations of social-cognitive factors (motivational and volitional factors) with three preventive behaviors (hand washing, facemask wearing, and physical distancing) in a mixed sample of older adults from China and Germany and to evaluate the moderating effects of countries. A total of 578 older adults (356 Chinese and 222 German) completed the online cross-sectional study. The questionnaire included demographics, three preventive behaviors before and during the pandemic, motivational factors (health knowledge, attitude, subjective norm, risk perception, motivational self-efficacy (MSE), intention), and volitional factors (volitional self-efficacy (VSE), planning, and self-monitoring) of preventive behaviors. Results showed that most social-cognitive factors were associated with three behaviors with small-to-moderate effect sizes ( = 0.02 to 0.17), controlled for demographics and past behaviors. Country moderated five associations, including VSE and hand washing, self-monitoring and facemask wearing, MSE and physical distancing, VSE and physical distancing, and planning and physical distancing. Findings underline the generic importance of modifiable factors and give new insights to future intervention and policymaking. Country-related mechanisms should be considered when aiming to learn from other countries about the promotion of preventive behaviors.