The purpose of the study was to explore the influence of Teachers External regulation Motivation on Learners’ Academic Achievement in Rachuonyo South Sub-County, Homa bay County. The objective was to find out the influence of teachers external regulation motivation on learners academic achievement. The study used parallel convergent design of the Mixed Method Approach and was informed by Self-Determination Theory Needs Perspective. The target populations were 81 head teachers, 324 class eight teachers and 1 SCQASO and sample of 24 head teachers, 97 class eight teachers and 1 SCQASO was established which were selected through purposive, stratified random and saturated sampling techniques respectively. Questionnaires and interview schedules were employed to collect data. Content validity was achieved through supervisor guidance while face validity was enhanced by arranging the questions from simple to complex order. Reliability was enhanced through pilot study. Quantitative data collected was analyzed using descriptive statistics, while qualitative data was analyzed using thematic analysis. On the concern of influence of External Regulation Motivation for Teachers on Learners’ academic achievement, study found that teachers lacked external regulation motivation because they are not motivated through monetary incentives, promotions, sponsored in-service trainings and educational tours. The study concludes that most teachers were not being motivated to put extra effort for leadership roles, nor given monetary rewards and free meals by their employers or school administrations at school, through promotions and sponsored in-service trainings. This implies that increase in extrinsic motivation of teachers helps to influence teachers’ motivation which may promote learners academic achievement. The study recommends that the Ministry of education should organize workshops, seminars, educational tours which are sponsored and monetary rewards offered to teachers. Teachers Service Commission should work on incentive salary and remuneration packages to increase teachers’ extrinsic motivation. A study on Relationship between intrinsic motivation and learners’ performance in primary schools would expound the present study