Introduction: Kenyan teachers showed signs of plateauing in employment. This research examined whether the career plateauing was related to of teachers seeking postgraduate studies. Purpose: The study aimed at determining the types of career plateuing faced by public school teachers in secondary schools and to determine the relationship between career plateauing and the decisions of teachers to undertake different postgraduate courses. Methodology: The research employed correlational study design. The target population was 5,022 teachers, and 304 from Nyandarua and 348 from Murang'a Counties. A representative sample was determined using the formula by Krejcie & Morgan, which is used to calculate a sample size of 652. A questionnaire was used for data collection, and its relevance was reinforced by the experience of supervisors and other lecturers at the university. Test-Retest methodology was used to determine the reliability of the questionnaire and found a correlation coefficient of 0.86. The data were analyzed using descriptive and inferential statistics. Pearson Product Moment correlation coefficient, variance analysis and chi-square were used at 0.05 level of confidence. Results: Most teachers in the study did not experience career plateauing. There was a significant relationship between structural plateauing and nature of postgraduate course attended although there was no significant relationship across the entirety of the courses attended and overall career plateauing. Recommendations: The Teachers Service Commission should create a consistent roadmap for teachers' career development to address career plateauing and, in partnership with the Ministry of Education, should improve teachers' skills upgrades through capacity-building initiatives that should form the basis for promotion.