This systematic review investigates the pedagogical competencies required for effective Content and Language Integrated Learning in mathematics classrooms with particular attention to EFL contexts. The study aims to identify the competencies teachers need, the instructional innovations that support content language integration, and the ways teacher-mediated assessment practices shape instructional outcomes. Addressing ongoing concerns with regard to teacher preparedness for multilingual mathematics education, the review highlights the significance of aligning mathematical reasoning with academic language development. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol, a structured search of Scopus and Web of Science (WoS) identified 22 peer-reviewed empirical studies published between January 2023 and November 2025. Thematic synthesis revealed three key areas: teacher professional competence and institutional capacity-building; pedagogical innovations and instructional design in CLIL and English-Medium Instruction classrooms; and teacher-mediated instructional outcomes and assessment practices. The findings indicate that effective CLIL mathematics teaching depends on sustained professional learning, strong institutional support and language-responsive instructional design. At the same time, assessment practices are crucial for aligning content mastery with language development. Overall, this review contributes a consolidated evidence base for competency-oriented teacher education and curriculum planning in multilingual mathematics education. The review concludes with recommendations for future research to examine long-term professional learning models and context-sensitive pedagogical frameworks that can better support teachers in diverse multilingual settings.