The study aimed to investigate the trade union practices on teacher performance in Kenya and evaluate the effectiveness of the Kenya Union of Post Primary Education Teachers' (KUPPET) social dialogue and welfare programmes in improving the performance of secondary school teachers in Homa Bay County. The performance of teachers in schools was crucial for the education sector's success, but several challenges could undermine their contributions. While trade unions played a significant role in protecting the rights of workers and enhancing their welfare, their influence on teacher performance in Sub-Saharan Africa, including Kenya, was a concern. The study employed a mixed-methods approach to collect data from secondary school teachers in Homa Bay County. Quantitative data was gathered through a survey questionnaire distributed to a random sample of 300 secondary school teachers. Qualitative data was collected through focus group discussions with teachers, KUPPET officials, and school administrators. The collected data was analysed using descriptive statistics, regression analysis, and content analysis. The study's findings provided insights into the trade union practices on teacher performance and the effectiveness of KUPPET's social dialogue and welfare programmes in improving teachers' performance in Homa Bay County. The study's results could inform policy-makers, education stakeholders, and trade union officials in designing and implementing effective policies and programmes to improve teacher performance in Kenya and other developing nations. In conclusion, the study was significant as it addressed research gaps in the effects of trade union practices on teacher performance specific to developing nations like Kenya. The study's findings had practical implications for education stakeholders, policy-makers, and trade union officials in promoting effective social dialogue and welfare programmes to improve teacher performance and enhance the education sector's quality.