Rural students face unique educational challenges affecting their transition to tertiary education. This descriptive-correlational study examined whether Senior High School STEM academic performance correlates with college readiness among 80 rural graduates from Bato, Leyte who enrolled in STEM undergraduate programs in 2025. Using a validated 20-item assessment based on Conley's framework, the study measured readiness across content knowledge, cognitive strategies, academic behaviors, and contextual skills and awareness. Despite high academic achievement (M = 91.4%, SD = 2.78), graduates reported moderate readiness (M = 74.4/100), with notable gaps in content knowledge (M = 17.5/25) and cognitive strategies (M = 17.7/25). Pearson correlation revealed significant positive relationships between GWA and all readiness dimensions (r = .373 to .465, p < .001), though academic performance explained only 21.6% of readiness variance. These findings suggest that while STEM performance contributes meaningfully to undergraduate program readiness, substantial additional factors influence readiness outcomes. The study provides empirical evidence for policy refinement and targeted interventions to strengthen rural STEM education effectiveness in the Philippines.