This project is on Effects of game based learning on junior secondary school student’s achievement in mathematics in Enugu. The purpose of the study was to determine the effects of game based learning on junior secondary school student’s achievement in mathematics. The work was a pre-test post-test control group quasi experimental research design. The researcher formulated two research questions and two hypotheses that guided the study. The researcher used mathematics achievement test as an instrument for data collection. The reliability of the instrument was 0.79 using Richard Kuderson formula 20 and the instrument was validated by three research experts. The population of the study was 950 and a sample size of 280 was obtained using the Taro Yamane’s simplified formula in the four selected Government secondary schools in Enugu East local Government Area of Enugu state. The Data collected was analyzed using mean, standard deviation for the research questions and t-test for the hypotheses analysis. The study revealed that game based learning is an interactive form of learning that gives learners the opportunity to work in group competitively and at the same time learn mathematics in a fun filled way. Results also show that male students perform better than their female counterparts when exposed to game based learning approach. The following recommendation was made, teachers should be trained on ways of using game based learning approach in the classroom and Educational planners should implement it in the school curriculum among others.