The main objective of the study was to investigate the effect of physical fitness on students’ academic achievement. Hypothesis had been formulated “there was no significant relationship between the physical fitness and academic achievement (GPA) of the students’. For this purpose, quasi-experimental research method was used taking 40 students as the study samples; these participants have been taken twelve minutes run(one mile run) test scores in meters, pull up test, push-up and sit and reach test as a pre-test. Regarding their academic achievement their 2017/18 grade 10 grade point average (GPA) was taken as a pre-test and the participants were taken a physical fitness pre-test and pot-test to figure out change in achievement obtained before and after intervention. For academic performance their 2018 grade 11 grade point average (GPA) was taken as a post-test. Then an intervention of physical fitness (physical activity) was held for twelve weeks (once a week for 50’ minutes each of cardio respiratory, muscular strength and endurance and flexibility events throughout the intervention, checklists were used to record the students performance zone and progresses each week in difference events. After the intervention was made post-test, an improvement was noticed in their physical fitness by a mean average difference of 37.725 and with a correlation coefficient of 0.845 analyzing through MICRO SOFT SPSS which was interparty very high relationship between the two physical fitness test. As their physical fitness performance zone improved, similarly, a significant positive effect has been shown on their academic performance. The mean average difference between the pre-test (GPA=45.6750) and post-test (GPA=51.4500) became 5.775 and the correlation coefficient became 0.774 as pearson product moment the correlation which was close to one and interpreted high relationship between them. From this, it was concluded that there is a positive relationship between physical fitness and academic performance. Based on the finding of the study, curriculum experts and teachers were recommended to put the positive effect of physical fitness for academic achievement during designing syllables and teaching physical education. TABLE OF CONTENT Contents Page