This study aims to determine the effect of time management and students' interest in learning mathematics on academic achievement, as well as the combined effect of these factors on student achievement. The study was conducted with a sample of 250 secondary school students in Palu, Indonesia, consisting of 98 male and 152 female students. Questionnaires and tests were used as research instruments. The regression equation modeling was analyzed using SPSS software (v. 25) with the ANOVA test. The results showed that time management significantly impacts student achievement, contributing 18.7 %. Interest in learning mathematics also significantly impacts student achievement, contributing 21.8 %. Moreover, time management and interest in learning mathematics together have a significant influence on student achievement, contributing 31.1 %. Based on the findings, it is recommended that school management provide periodic sessions on time management at the beginning of each academic year and implement engaging mathematics learning strategies to enhance student's interest and academic performance.