Abstract: The paper reports findings of a study that sought to examine the effect of innovative teaching methods on students’ mathematics self-efficacy in three-dimensional geometry in public day secondary schools in Musanze District, Rwanda. The study was based on Self-Efficacy Theory and Social Cognitive Theory. A mixed-methods research design employing quasi-experimental and descriptive approaches was used for the study. Multistage sampling techniques were used to select a sample of 269 students from public day secondary schools in Musanze District. Students’ mathematics self-efficacy questionnaires, achievement tests, and semi-structured interview guides were used to collect data from respondents. Quantitative data were analyzed using descriptive statistics and an independent samples t-test, while qualitative data were analyzed thematically. The results indicate that students exposed to innovative teaching methods attained slightly higher mathematics self-efficacy scores than students taught using traditional instructional approaches. However, the difference was not statistically significant, indicating that innovative teaching methods did not significantly influence students’ mathematics self-efficacy beliefs in three-dimensional geometry. The study provides a basis upon which mathematics teachers, curriculum developers, and educational policymakers can strengthen learner-centered instructional approaches and create supportive learning environments that promote students’ confidence, motivation, and participation in mathematics learning.