Principal’s leadership practices have significant role in influencing work environment and job satisfaction among teachers in Senior schools. This study examined the effect of principals' decision-making practices on teacher job satisfaction in public Senior schools in Sirisia Sub-County, Bungoma County, Kenya. The study was guided by the Transformational Leadership Theory and Herzberg's Two-Factor Theory. The study adopted A descriptive survey research design, targeted a population of 600 teachers drawn from 30 public Senior schools in the sub-county. A stratified random sample of 240 teachers was selected using Yamane's formula. Structured questionnaires administered to teachers were used for data collection. Out of the 240 distributed questionnaires, 192 were completed and returned, representing an 80.0% response rate. Cronbach's Alpha was used to measure the reliability of the study questionnaire, and an Alpha of 0.781 was achieved, confirming its reliability. Descriptive statistics, Pearson's Correlation, and simple linear regression were used for data analysis, with the help of IBM SPSS Statistics. The results showed that principals in Sirisia Sub-County have moderate inclusive decision-making practice (mean = 3.737, SD=1.108). The highest-rated decision-making practices were fairness (mean= 4.000, SD=0.965) and transparency (mean= 3.854, SD=1.074), whereas direct teacher involvement in decision-making was rated lowest (mean= 3.438, SD=1.251). A positive and statistically significant relationship was reported between decision-making practices and teacher job satisfaction (r = .742, p = 0.021<0.05). Decision-making practices significantly predicted teacher job satisfaction (β = 0.756, p = 0.002<0.05), accounting for 55.0% of the variance in job satisfaction. Based on the results of the study, it was concluded that fair, transparent, and consultative decision-making practices are significant influencers of job satisfaction among teachers. The study recommends that structured measures for decision-making, including the use of anonymous suggestion systems and rotating committee representation, should be developed to improve teachers’ participation in the decision-making process and their overall job satisfaction.