This dissertation aimed at assessing the contribution of school rules and regulations in enhancing students‟ discipline and academic performance in secondary schools in Karatu district. The reason to conduct this study was due to poor academic performance of students in secondary schools in Karatu district, thus the researcher wanted to find out how school rules and regulations contributed to students‟ discipline as well as students‟ academic performance. The study was guided by four objectives; students‟ perception of school rules, implementation of school rules, contribution of school rules towards academic performance and challenges facing teachers in enforcement of such rules. The study was guided by X and Y theory and social control theories. A mixed research approach was used where explanatory sequential research design was employed in data collection. The sample size selected included 4 head of schools, 4 discipline masters, 85 teachers and 70 students who responded to questionnaire and interview guide. The findings revealed that students did not like school rules and regulations though such rules seemed to be fair and favourable to students however, teachers strictly implemented such rules for maintaining students‟ discipline for better academic achievements. Furthermore, school rules and regulations had huge contribution to students‟ academic performance because those rules made students attend classes and participated highly in their studies since teachers were effectively teaching. Although there were some challenges, teachers were able to provide conducive environment for students‟ learning as well as encouraging parents to participate in students‟ wellbeing. It was recommended that schools need to organize seminars and campaigns to education stakeholders about maintaining students‟ discipline and academic performance and explaining on the importance of obeying school rules and regulations.