This study aims to investigate the effect of the teaching efficacy of early childhood teachers and classroom environment on the school readiness of five-year-old children through the mediating effect of teacher–infant interaction. The study used the seventh-year data (2014) of the Panel Study on Korean Children by the Korean Institute of Child Care and Education. Out of 1,620 children aged 70 79 months and their teachers, data were collected from 1,054 infants attending kindergartens and daycare centers. To examine the relationship and influence among variables, statistical analysis was performed using a structural model, wherein the fit of the model was found to be very good. The result indicates that the mediating variable, that is, teacher–infant interaction, exerted a positive effect on the school readiness of five-year-old children. However, the relationship between the teaching efficacy of early childhood teachers and the classroom environment did not seemingly exert a direct effect on the school readiness of the children. Second, the teaching efficacy of early childhood teachers and classroom environment were found to exert an indirect effect on the school readiness of the five-year-old children through the mediating role of teacher–infant interaction. In addition, this mediating effect was considered significant after verifying through bootstrapping.