Engaging in online gaming is often considered as an avoidance strategy to cope with stress. This study aimed to test whether metacognitions make a unique contribution and which of them is/are the most salient to explaining Internet Gaming Disorder (IGD) tendency after controlling for age, gender, and stress. We further explored the structure of relationships between these variables by testing a metacognitively mediated stress-IGD model. A convenience sample of 1255 Chinese young adults with gaming experience (age ranged from 18 to 27; 57.0% females) completed an anonymous online questionnaire in June 2021. Each metacognitions subscale was positively correlated with IGD tendency, whilst cognitive confidence and positive beliefs about worry were identified as the most salient dimensions among metacognitions for IGD tendency after controlling for demographics and stress. The mediation path model showed acceptable fit after implementing minor modifications. The bootstrapping results showed that the effect of stress on IGD tendency was fully mediated, with metacognitions and escape motivation as independent mediators. In the model, the paths from both positive metacognitions and uncontrollability/danger metacognitions to escape motivation (and in turn IGD) remained significant, whilst the path between cognitive confidence and IGD also remained significant. The findings suggest revisions to the stress-coping model consistent with self-regulatory executive function theory, and advance our understanding of the potential risk factors linking stress to problematic gaming. Enhancing individuals’ capacity for metacognitive regulation may be an effective approach for future IGD preventive interventions among Chinese young gamers.