This study aims to implement CyberMonopoly, a serious board game-based learning medium designed to align with the characteristics of junior high school students, and evaluate its effectiveness in improving their understanding of fundamental cybersecurity concepts. The study employed a quantitative approach using a pre-experimental one-group pretest–posttest design. The participants comprised 26 eighth-grade students from SMP Negeri 2 Purwakarta, Indonesia, who were selected through saturated sampling. Data were collected using a 20-item questionnaire administered before and after the learning intervention. The data were analyzed using descriptive statistics, the Shapiro–Wilk normality test, the Wilcoxon signed-rank test, and N-gain analysis. The findings showed an increase in the mean score from 52.85 on the pretest to 89.31 on the posttest. The Wilcoxon signed-rank test revealed a statistically significant difference between the pretest and posttest scores (Z = −4.461, p < .001), with all 26 participants showing an improvement in their scores. Furthermore, the mean N-gain score was 0.78, indicating a high level of improvement. Students also demonstrated active participation and positive interactions throughout the learning activities. The novelty of this study lies in the development and empirical evaluation of a non-digital board game-based learning medium that presents cybersecurity concepts within contexts relevant to junior high school education. Overall, CyberMonopoly shows potential as an innovative supplementary learning medium for strengthening students’ understanding of fundamental cybersecurity concepts.