The Philippines has ranked among the lowest-performing participants in the Programme for International Student Assessment (PISA), scoring 355 in mathematics in 2022 against an OECD average of 472, with only about 16% of students reaching baseline (Level 2) proficiency. This study maps the research literature that has grown around Filipino students’ mathematics performance and identifies the explanatory factors foregrounded by this body of work. A corpus of 2,070 records (2000–2025) was retrieved from OpenAlex and screened to 1,556 relevant Philippine mathematics-education studies through a triple-gate filter (Philippine locus, mathematics signal, and education signal). Bibliometric indicators were computed in Python, and the explanatory factors were identified through deductive lexical coding of titles and abstracts against a nineteen-category vocabulary, followed by co-occurrence, thematic-map, and temporal analysis. The field is young, expanding rapidly (18.22% annual growth), and highly fragmented across 584 sources and 3,379 authors, with production concentrated in teacher-education universities. The literature emphasizes proximate and affective factors—technology, teaching strategies, curriculum, engagement, and attitudes—while structural determinants implicated by PISA and the national literature—socioeconomic status, language of instruction, school-resource, and teacher quality—remain peripheral and internally underdeveloped. Research has recently pivoted toward foundational numeracy and engagement, mirroring post-pandemic learning-recovery policy. The central contribution is the demonstration of a proximate–structural asymmetry that marks a priority gap for future research and policy. For policy makers, the evidence map suggests that improving mathematics performance requires not only better classroom strategies, technologies, and curricula, but also coordinated attention to poverty, language access, teacher preparation, and school-resource inequality.