This study examined the impact of the Rwanda African Institute for Mathematical Science, Teacher Training Program (AIMS-TTP) on 228 secondary school students’ interest to learn Mathematics and science taught by 7058-trained teachers over 5-years across 14 districts. Students were exposed to various AIMS-TTP interventions, including industrial visits, science hours, and international day for women and girls in science, mathematics competition, robotics and mathematics challenge, and the Pan African Mathematics Olympiad (PAMO). A survey research design was employed to collect data about students’ interest to learn Mathematics and science, and data on students’ choices of combinations were obtained from the National Examination and School Inspection Authority (NESA) for the academic years 2017 to 2022. Data analysis using bivariate correlation and regression analyses revealed a positive and significant relationship (p<.05) between AIMS-TTP interventions and students’ interest to learn Mathematics and science. Besides, linear regression model indicated that hands-on activities, exposure to mathematics and science role models, science hour and smart classroom were the best predictors of students’ interest to learn mathematics and science (β=.197, p< .05; β=.217, p<.05; β=.234, p< .05; and β=.218, p<.05 respectively). They contributed 66.7 % (Adjusted, R2 = .667, p < .05) of the variance in students’ interest in learning mathematics and science. The AIMS-TTP interventions significantly improved students’ interest to learning mathematics and science. Recommendations include comprehensive training programs with direct student engagement, diverse competitions, and ongoing teacher support through professional development. Future research should focus on students’ STEM interest in Technical, Vocational Education, and Training schools.