Background and aims: Internet Gaming Disorder (IGD) and depression have negative consequences on individuals' mental health, but their relationships are complex. This three-wave longitudinal study aimed to detect the metacognitive mechanisms underlying the association between IGD tendency and depression based on the self-regulatory executive function model. Methods: A total of 1,243 Chinese undergraduate student gamers (57% female, M = 19.77, SD = 1.29) were recruited at the baseline survey (Wave 1 [W1]), with 622 and 574 of them taking part in the two follow-up surveys (Wave 2 [W2] at 6 and Wave 3 [W3] at 12 months later), respectively. Results: The three-wave path model demonstrated, after controlling for the autoregressive effect of each variable, that depression consistently predicted IGD tendency but not vice versa, while negative but not positive metacognitions about online gaming (MOG) significantly predicted both depression and IGD tendency. Moreover, two statistically significant mediation paths: (i) negative MOG [W1] → depression [W2] → IGD tendency [W3]; and (ii) depression [W1] → negative MOG [W2] → IGD tendency [W3] were identified. Discussion and conclusions: These findings extend the understanding of the associations among depression, IGD tendency, and MOG, highlighting how negative MOG has a stronger prospective effect than positive MOG on depression and IGD tendency, and also reveal the mutual mediation effects of depression and negative MOG on IGD tendency. Integrated programmes with both emotional regulation training and Metacognitive Therapy are recommended for IGD treatment.