This study investigated the relationship between School Improvement Planning (SIP) implementation and Academic Achievement (AA) among 114 educators in the District of Sto. Tomas West. Specifically, the research assessed the implementation extent of SIP’s five pillars (goal setting, stakeholder engagement, resource allocation, evidence-based practices, and monitoring mechanisms) and the level of student achievement across four markers (standardized assessments, graduation rates, student growth percentiles, and school quality markers). It also determined whether a significant relationship exists and identified which specific components serve as significant predictors of academic achievement. A quantitative correlational design was utilized, with data gathered via validated, pilot-tested survey questionnaires. Statistical analyses included mean scores, Pearson’s correlation, and multiple regression analysis. The findings revealed that the overall implementation of SIP is moderately extensive, indicating collaborative, research-oriented schools that must still refine technical accountability frameworks and maximize resource efficiency. Meanwhile, the district maintains a high level of academic achievement, though enhancing long-term graduation rates requires continued strategic resource management and community-focused support. Notably, a significant positive relationship exists between SIP implementation and academic achievement, demonstrating that effective school planning is a vital catalyst for student success. Furthermore, regression analysis identified the Implementation of Evidence-Based Practices as the most critical driver of student achievement. Based on these findings, it is recommended that schools strengthen support for at-risk students and shift monitoring mechanisms from technical compliance to supportive feedback loops to sustain long-term educational growth.