This study aims to investigate the impact of utilizing the Guided Discovery Learning (GDL) model supported by YouTube on enhancing self-efficacy and mathematical analysis abilities among junior high school students. Adopting a quantitative approach, this research was structured as a quasi-experimental design with a post-test only control group arrangement. Data was collected through subjective questionnaires, descriptive questions, and documentation. Data analysis was conducted using MANOVA with the aid of SPSS version 25. The findings indicate a significant difference in self-efficacy and mathematical analysis skills between students who participated in learning using the GDL model supported by YouTube compared to those who engaged in GDL without YouTube and expository learning methods. MANOVA testing, following the tests for data normality and homogeneity, affirmed the effectiveness of the YouTube-assisted GDL model in enhancing both variables. This study confirms that the application of the Guided Discovery Learning model with YouTube support significantly improves self-efficacy and mathematical analysis skills in junior high school students compared to other learning methods. This highlights the potential of integrating online resources like YouTube into teaching methods to facilitate more interactive learning experiences and improve student learning outcomes.