In school system, the teacher is the key input as he/she is the one to create a conducive atmosphere for learning by preparing the learning content, preparing classroom environment, ordering materials, using a variety of methods to deliver learning, and he/she also assesses the level of learners, manages time and students, and should be a good role model. Therefore, the purpose of this study was to determine whether and to the extent to which relationship exists between teacher characteristics and school performance in public secondary schools in Nyamasheke and Nyarugenge districts. Specifically, the study sought to describe teacher characteristics, determine the extent to which teacher characteristics correlate with school performance, and find out the strategies adopted to enhance school performance in public secondary schools located in the two districts. This study was guided by Education Production Function theory and it adopted a correlation research design. The target population involved 70 head teachers and 2 district education officers. 21 head teachers and 2 district education officers were surveyed. Stratified sampling, simple random sampling and purposive sampling techniques were used to select this sample and questionnaires, document review schedule, and interview schedule were used to collect data. It was found that only 61.15% of teachers have a bachelor’s degree, among them only 63.81% have undergone a pedagogical course, and only 56.05% have an experience of more than three years. It was further found that among the teacher characteristics, teacher qualification, professional training and experience highly correlate with school mean performance and as the coefficient of determination for each varies between 0.41 and 0.63. It was therefore recommended that the government and all other stakeholders should allocate more resources to train more teachers and retain experienced ones and provide more in-service training to enhance teachers’ professionalism.