This study explored HEXACO personality traits and the prediction of academic achievement through personality traits and demographic variables. This study also explored gender differences in personality traits and academic achievement. The sample comprised 377 school-going students. HEXACO–PI was used to measure the personality traits of students. Self-reported GPA was collected from the students to measure academic achievement. The results showed significant gender differences in the E trait only. Academic achievement did not differ significantly for gender. Results showed that X and C traits showed a significant correlation with academic achievement. Further, 23.1% of the variation in academic achievement was predicted by the combined effect of personality traits and demographic variables. Further, extraversion and conscientiousness were the significant independent predictors of academic achievement. Thus, personality traits should be considered to improve students’ academic achievement.