There is limited research on the teaching competence of mathematics teachers in the Philippines Alternative Learning System (ALS). This study examined how the individual, institutional, and contextual factors influence the teaching competence of ALS mathematics teachers. A survey research with a quantitative, descriptive-correlational research design was used, involving 114 ALS mathematics teachers from the six (6) school divisions of the Department of Education (DepEd) in Region XI, Southern Philippines, selected through stratified random sampling. Guided by Bronfenbrenner's Bioecological Theory and Bandura's Self-Efficacy Theory, the study utilized multilevel analysis to account for the hierarchical structure of the data. Results of the multilevel analyses showed that mathematics teaching efficacy, mentorship, collaborative teaching, and community linkages significantly predicted teaching competence. The findings shed light on the key factors that shape teaching competence in ALS, linking teaching competence to a combination of individual teaching skills and institutional support. This study provides policymakers, program managers, and educational leaders with evidence-based information to support quality mentoring and collaborative teaching and to design context-responsive educational support. The findings have potential application in designing high-quality professional development activities to improve teaching competence in non-formal education environments.