Childhood immunization can effectively control and prevent infectious diseases; however, not all parents choose to vaccinate their children against vaccines, including COVID-19. This study aimed to determine potential factors influencing people's willingness to vaccinate their children. An online survey was conducted with 509 adult parents/guardians of children to test our hypotheses. Based on the TPB model with the RISP model as the antecedent, results indicated that people's systematic risk information processing, trust in science, and concerns about the disease positively influenced their cognitive structure, further impacting their attitude toward vaccinating their children. The results also verified that attitude toward vaccination and perceived behavioral control are both significant predictors of parents/guardians' intention to vaccinate their children. The results contribute to health risk communicators creating effective strategies to better communicate with adults and increase intentions to vaccinate their children.