This study explored the structural relationship among growth mindset, academic grit, and academic burnout. This study investigated the impact of Korean high school students' growth mindset on their academic burnout. Also, it is this study's contention that the effect of growth mindset on academic burnout can be changed when academic grit as a persistent enthusiasm and effort in their studies are mediating. The sample of this study comprised 573 Korean high school students (aged 17 years) in 2018. This study was designed as correlational research, and data analysis was conducted mainly using structural equation modelling. This study found that growth mindset may act as a diminishing factor for academic burnout. In addition, this study found that academic grit negatively mediated the relationship between growth mindset and academic burnout, implying that academic grit can play a determinant role as a positive psychological variable that could alleviate or prevent academic burnout. Thus, programming and counseling oriented toward fostering academic grit and coupled with growth mindset should be provided to lessen or prevent academic burnout. This study fills a void in the literature on academic grit and on growth mindset in targeting academic burnout among high school students preparing for college entrance examinations.