Education is a fundamental human right which promotes acquisition of knowledge and skills for development. Despite efforts by policy makers, administrators, teachers and learners to improve learner achievement, performance remains poor (MOEST, 2012). The purpose of this was to establish the influence of teacher motivation on promoting student’s academic achievement in public secondary school education. The study adopted concurrent triangulation research design. The target population for this study was 184 public secondary schools, 1233 teachers, and 73,385 learners. A sample involving 56 public secondary schools whereby 56 principals, 370 teachers and 398 learners was drawn from target population. Purposive sampling was used to get 56 schools, simple random sampling was used to get 370 teachers and stratified random sampling technique was used to get 398 learners. Data for the study was collected by the use of three different questionnaires and three different interview schedules. Validity of questionnaires was tested during the pilot study in Homa-Bay County which is neighboring Migori County. Split Half reliability test which is a measure of internal consistency was used. All pre-testing procedure for Reliability of instruments was based on reliability coefficient of 0.79 indexes. The data collected was summarized and analysed qualitatively and quantitatively. Inferential statistics was used whereby Correlation, Regression and Chi-square tests were used to gauge influence of teacher motivation on student academic achievement. The research revealed that teacher motivation had no significant influence on learner academic achievement in secondary schools Therefore, the study concluded that administrators should put in place measures to enhance teacher Motivation. In conclusion, institutional managers should design proactive processes that can inculcate positive support for teacher motivation.