Objective: This study explored the relationship between early childhood teachers’ teaching efficacy, teacher-child interaction, and preschoolers’ school readiness. Methods: The data were drawn from the seventh wave of the Panel Study on Korean Children. The subjects of this study were 1,150 preschoolers and their teachers. Early childhood teachers reported their teaching efficacy, their interaction with preschoolers, and preschoolers’ school readiness. Data were analyzed using structural equation modeling. Results: First, early childhood teachers’ teaching efficacy did not have a direct effect on preschoolers’ school readiness. Second, early childhood teachers’ teaching efficacy had an indirect effect on preschoolers’ school readiness through teacherchild interaction. In other words, teachers with a high level of teaching efficacy had high-quality interactions with preschoolers, which led to preschoolers showing a high level of school readiness. Conclusion/Implications: The results of this study highlight the importance of teachers’ high teaching efficacy and high-quality interactions between teachers and preschoolers to improve preschoolers’ school readiness. In addition, this study contributes to a better understanding of the mechanism by which teachers’ teaching efficacy influences preschoolers’ school readiness.