Despite widespread use of serious games in education, there is a significant gap in standardized approaches for validating educational content. This research develops a systematic framework specifically for content validation in serious games, examining two cybersecurity games created for children aged 8–13 as part of the “SuperCyberKids” Erasmus+ initiative. Through a two-step scoping review analyzing databases across pedagogy, psychology, and computer science disciplines, we identified contemporary approaches to creating and validating serious game content. The study presents a novel three-phase validation model comprising initialization, theoretical content validation, and practical content validation. This framework aims to ensure serious games fulfill their intended learning objectives while delivering effective educational experiences. Following the scoping review, we implemented a survey with 20 experts who evaluated the content of two cybersecurity games, “Spoofy” and “Nabbovaldo.” Findings indicated that both games generally offered strong content coverage across their domains, though specific gaps were identified requiring additional instructional materials.