The purporse of this study was to investigate the factors affecting students’ academic performance in geography in geography in public secondary schools in Ngong sub-county Kajiado county Kenya. The objectives of the study were: to find out whether teachers’ methodology affects students’ academic performance in geography, to investigate whether students’ attitude toward geography affects students’ academic performance in geography and to examine whether school environment affects students’ academic performance in geography. In order to achieve these objectives, the researcher administered questionnaires to the students and teachers from selected schools in the study area. Both the students and teaches were sampled purposively to include all form three and four geography students and teachers. The study used descriptive survey design and adopted quantitative approach. The study enlisted 85 respondents comprising 76 students and 9 teachers. The Statistical Package Social Sciences (SPSS) was used to get descriptive statistics. The findings showed that, most teachers used useful teaching methodology which were ideal for improving students’ performance in geography. The study noted that, students had positive attitude towards geography and found it interesting. The respondents also agreed that, most schools under the study had conducive environment for teaching and learning geography. However, most schools were lacking updated and revised textbooks for teachers and students and variety of teachings methods. Therefore, the researcher recommended that the schools adeministrators should strive to provide morea adequate textbooks for teaching and learning geography