Mathematical Knowledge for Teaching (MKT) has emerged as a critical construct in mathematics education research, recognized as a strong predictor of students’ mathematical achievement. This study aims to examine the dimensions of MKT among preservice elementary teachers in Indonesia, focusing on their readiness and competence in both content and pedagogy. Using a teacher-made instrument specifically designed to assess MKT, data were gathered from preservice teachers enrolled in teacher education programs. The instrument measured four key domains: Common Content Knowledge (CCK), Specialized Content Knowledge (SCK), Knowledge of Content and Students (KCS), and Knowledge of Content and Teaching (KCT). The findings revealed that preservice teachers demonstrated generally low proficiency across all MKT domains. Their limited performance in both content and pedagogical aspects suggests that they are not yet adequately prepared to teach elementary mathematics effectively. Among the four domains, the lowest scores were observed in SCK and KCT, highlighting weaknesses in linking mathematical concepts with instructional strategies and student thinking. This indicates a pressing need for teacher education programs to provide more comprehensive and integrated coursework that explicitly develops both content and pedagogical knowledge. Moreover, the study underscores the importance of reforming mathematics teacher education curricula in Indonesia to better align theoretical understanding with practical classroom applications. Strengthening preservice teachers’ exposure to real teaching scenarios, problem-based learning, and reflective practices may enhance their MKT and overall teaching readiness. The results contribute to the growing international discourse on teacher knowledge, emphasizing that improving preservice teachers’ mathematical understanding is vital for achieving high-quality mathematics instruction in schools. In conclusion, this study highlights a significant gap between the current level of mathematical knowledge among preservice teachers and the competencies required for effective mathematics teaching. It calls for a strategic redesign of teacher education programs that prioritize the deep integration of mathematical content, pedagogical reasoning, and contextualized teaching experiences.