This study examined the interrelationships among playfulness, prosocial skills, and school readiness of Hong Kong kindergarten children across time. Participants were 106 local children (55.6% boys, mean age = 60.0 months) and their parents and teachers. At time 1, parents reported their child's age, gender, and playfulness. Six months later at time 2, teachers reported children's prosocial skills and school readiness. The structural equation model revealed that children's playfulness at time 1 significantly predicted their prosocial skills at time 2, and that their prosocial skills and school readiness at time 2 were positively associated. The indirect relationship between playfulness and school readiness as mediated through prosocial skills was significant, whereas the direct relationship was non-significant. These findings suggest that children's playfulness may contribute to school readiness by fostering prosocial skills. Practically, results highlight the utility of promoting children's playfulness and prosocial skills to support their formal school transition.