This research explores the impact of integrating Reflective Pedagogy within Mathematical Knowledge for Teaching (MKT), framed by the TPACK model, on enhancing mathematics proficiency in Rwandan Teacher Training Colleges (TTCs). The study involved 433 Year 2 TTC students in the Science and Mathematics Education program using a quasi-experimental design. Reflective Pedagogy was incorporated into MKT through structured lesson planning, observation, and feedback. Data collection included pre-and post-tests, teacher training, and item analyses of a mathematics performance test. Results indicated significant score improvements for both groups, with the experimental group excelling in algebraic expressions, probability, and mathematical modeling. Notably, the control group showed higher proficiency in understanding the inverse of a function, suggesting varying pedagogical impacts across mathematical concepts. Findings underscore the potential of MKT Reflective Pedagogy to enhance mathematics proficiency, offering insights for educational practitioners and policymakers in Rwanda and beyond. Targeted TPACK and Reflective Pedagogy training for TTC tutors is essential to foster innovative teaching approaches aligning with the goals of 21st-century education.