<p>Given the growing concerns of gambling in online gaming among youth in Hong Kong, understanding contributing factors of potential for gambling in online gaming becomes increasingly important. This study aims to test the associations between internet gaming disorder (IGD), online gambling tendency, and the potential for gambling in online gaming among Hong Kong youth. Data from a sample of 1,661 youth from July 2020 to August 2020, and were analyzed using multiple regressions and mediation models. The results showed that both IGD (<i>b</i> = 0.04, <i>p</i> &lt; 0.001, 95% C.I. [0.03, 0.04]) and online gambling symptoms (<i>b</i> = 0.04, <i>p</i> &lt; 0.001, 95% C.I. [0.03, 0.04]) were positively associated with the potential for gambling in online gaming (standardized factor score). Mediation analyses with 10,000 bootstrap samples indicated significant indirect effects of IGD on gambling-in-gaming via online gambling symptoms (<i>b</i> = 0.01, <i>p</i> &lt; 0.001, 95% CI [0.00, 0.01]) and of online gambling symptoms on gambling-in-gaming via IGD (<i>b</i> = 0.01, <i>p</i> &lt; 0.001, 95% CI [0.01, 0.01]), controlling for demographics. These findings suggest that when online games and online gambling share similar reward and monetization features (e.g., rapid feedback, intermittent reinforcement, and chance-based purchases), adolescents may be more likely to develop problems in both domains. Developmentally appropriate intervention and prevention are needed to reduce the potential for gambling in online gaming among Hong Kong youth.</p>