The research examined the influence of teacher professional development (TPD) on the quality of teaching mathematics in public secondary schools in Rwanda. A Case of Burera District. Specifically, the research was assessing the effect of pre-service training on teachers’ performance in selected public secondary schools in Burera District, Rwanda, determining the effect of induction training of teachers on teachers’ performance in selected public secondary schools in Burera District, Rwanda, and establishing the effect of continuous teacher professional development of teachers on teachers’ performance in selected public secondary schools in Burera District, Rwanda. The sample size was 4012 respondents, with a sample size of 364 participants. This study used primary sources like questionnaires and interviews to gather data, using purposive, stratified, and simple random sampling methods. It employed both quantitative and qualitative methodologies, including content analysis and descriptive statistics. For the first objective, results indicate that 53.8% strongly agreed that Better skilled teachers are more likely to be better inspired and achieve better than inadequately trained teachers, 76.9% strongly agreed that Pre-service teacher training in Rwanda is too abstract, 84.6% strongly agreed that Pre-service teacher training deprives teachers-to-be from the encounters of classroom management of the learning process and 92.3% strongly agreed that Pre-service training of teachers is essential and helps in organizing different programs for pre-service training, updating and upgrading incoming and working educators at all levels and , and 84.6% strongly agreed that Teachers who receive adequate pre-service training performed better in the schools. For the second objective, 92.3% strongly agreed that the lack of induction training impairs TPD, 84.6% strongly agreed that induction training is important for teachers’ PD, 76.9% Strongly agreed that there are challenges with professional development for teachers, 69.2% Strongly agreed that the government, non-governmental organizations, and school authorities can and should do to make teachers’s professional development better. 61.5% Strongly agreed that the lack of induction training impairs TPD and 84.6% Strongly agreed that induction training is important for teachers’ PD. The study found a strong positive relationship between pre-service training, teacher motivation, engagement, and content expertise. It also showed a positive relationship between continued teacher professional development and content expertise, motivation, and engagement. Additionally, a significant correlation was found between teacher integrated pedagogical training and content expertise, motivation, and engagement, with a high attractiveness rate, indicating a positive relationship between these factors. These findings suggest that teacher professional development can influence the quality of teaching mathematics and were positively and statistically correlated since most of their level of significance was more than 0.05 in association with the quality of teaching mathematics in public secondary schools in Rwanda. Recommended that to enhance student learning, encourage active participation through discussions, debates, and hands-on activities. Promote teamwork and collaboration through group projects and real-world scenarios. Regular feedback and technology integration enhance learning experiences. Adapt teaching strategies to meet diverse learning needs. Use formative assessments to monitor progress and improve metacognitive skills. Encourage curiosity and creativity, and create a safe, inclusive environment. Develop positive relationships with students to foster social-emotional competencies.