<p>This study explored the implementation and effectiveness of a nationwide, open-access online preparatory program for potentially gifted science students in Korea. Twenty-seven university-affiliated gifted science education centers developed the Online Preparatory Program for Gifted Science Education to provide inquiry-based and self-directed learning to students in grades 5–7 who do not have prior gifted identification. The program reflects a shift toward inclusive and exploratory gifted education by allowing voluntary participation and providing opportunities to demonstrate scientific interest and competence through challenging tasks, rather than relying on early formal identification. A mixed-methods design was employed, drawing on three data sources: learning analytics from 1,479 participants, post-program survey responses from 541 students, and qualitative analysis of student-submitted assignments. Results revealed sustained engagement in task completion despite a gradual decline in weekly attendance. Students reported high levels of satisfaction and demonstrated motivation to complete inquiry-based assignments. However, communication opportunities received lower ratings, highlighting the need to improve interaction in online learning settings. The findings also revealed meaningful engagement in scientific reasoning, hypothesis generation, and problem-solving, suggesting that open-access online programs are effective platforms for exploratory learning among students with latent scientific potential. This study contributes to discussions about expanding access to gifted science education and provides a scalable model for performance-based talent development.</p>