This study inquired on the effect of Mastery learning Approach (MLA) in enhancing the academic achievement of mathematics. Eighty first-year senior secondary schools (SS 1) students were used as subjects of the study. Mastery learning approach was used in the treatment group (N=40) while the traditional teaching method was employed for the control group (N=40). This investigation utilized the quasi-experimental design. The results of the study showed the students who were exposed to mastery learning had enriched academic achievement in mathematics. Apparently, results on the posttest mean scores of the students revealed that there is a significant effect on the academic achievement of the experimental group in which the MLA had been introduced. As such, students exposed to MLA performed better than students who were taught in the traditional teaching method. Moreover, results exemplify that there is a significant relationship between the students’ attitudes toward mathematics and their academic achievement in mathematics.