School principals’ decisions commonly combine professional experience, policy demands, and available information. Nevertheless, when decision processes lack data-quality checks, evidence triangulation, option appraisal, and a documented rationale, decisions may become reactive and overly dependent on intuition. This study aimed to develop and test an evidence-based educational administration model for improving principals’ decision-making in Bengkulu Province, Indonesia. The study employed Research and Development using the ADDIE model: analysis, design, development, implementation, and evaluation. The needs analysis involved 60 principals; five experts validated the prototype; 12 principals participated in a limited trial; and the field test used a quasi-experimental pretest-posttest comparison-group design with 48 principals assigned to experimental and control groups. The product was the EVIDENCE Cycle, comprising eight stages: establishing the problem, verifying evidence quality, integrating multiple evidence sources, developing alternatives, engaging stakeholders, navigating criteria and risks, communicating and implementing the decision, and evaluating outcomes. Expert validation produced a mean Aiken’s V of 0.90 (very valid), while limited-trial practicality reached 88.9%. In the field test, the experimental group’s decision-making competency score increased from 63.08 to 81.75, whereas the control group increased from 62.54 to 69.66. The between-group gain difference was significant, t(46)=5.71, p<.001, with Cohen’s d=1.65. The model was therefore valid, practical, and effective in helping principals transform fragmented data into transparent, context-sensitive, and monitorable decisions.