Primary school teachers' pursuit of higher academic qualifications of degrees and diplomas goes hand in hand with upgrading and updating of their skills and abilities, which should be of consequence to the quality of their work performance. The purpose of this study was to examine the influence of primary school teachers' pursuit of academic advancement on work performance among public primary schools in Mumias West sub county, Kenya. The study was guided by correlational design. The population targeted by the study included 846 primary school teachers and 47 deputy head teachers of the 47 public primary schools in Mumias West sub-county of Kakamega county, Kenya. Respondents included 20 head teachers, 20 deputy head teachers and 240 teachers randomly sampled from selected schools. Data was obtained by use of questionnaire and document analysis guides. It was analyzed descriptively using frequencies and percentages. Hypothesis was tested using t-test. The study found that: the number of teachers who had advanced in their academics to attain diplomas and degrees was higher than those who had not; the main reason why teachers pursued academic advancement was to position themselves for promotion; the teachers' mean rating on their job performance was above average; teachers who had advanced academically to attain higher academic qualifications had a higher work performance rating. The study concluded that teachers' academic advancement had a positive influence on work performance among public primary schools in Mumias West Sub-County, Kenya. The study recommends that the government should recognize and reward higher academic qualifications attained by primary school teachers; the Ministry of Education should create and operationalize policies that can encourage primary school teachers to pursue higher academic qualifications; school administrators should create an enabling environment in schools that can eliminate gender disparities in work performance. The overall necessity of this aspect of professional advancement is grounded in the fact that the quality of a teacher influences the entire learning process.