Objective: At present, research on the neural mechanism of Internet gaming disorder (IGD) has predominantly concentrated on the prefrontal-striatal pathway, with the regulatory role of the cerebellum remaining to be systematically elucidated. We integrated multimodal neuroimaging to elucidate cerebellar circuitry in IGD pathogenesis. Methods: A total of 66 subjects with IGD and 46 recreational game use (RGU) were collected for the study. Multi-voxel pattern analysis (MVPA) employed support vector machines (SVM) with leave-one-out cross-validation, using regional homogeneity (ReHo), amplitude of low-frequency fluctuation (ALFF), and gray matter volume (GMV) features. Highly weighted brain regions recurring in multiple models were screened as regions of interest for granger causality analysis (GCA) to establish a whole-brain effective connectivity network and explore their effects on IGD severity. Results: The functional models independently and significantly discriminated IGD, while the structural model exhibited suboptimal performance. However, the multiple complementary models established that the high discriminative hubs of IGD included the right superior parietal gyrus, cerebellar Crus I/II, and lobule VIIb. Further GCA studies revealed a reduction in the bidirectional connections of the right superior parietal gyrus back to the bilateral lingual gyrus and the left middle temporal gyrus; the effective connectivity from the right middle frontal gyrus to the right Crus I and the right Crus II were decreased; However, efferent connections from the right cerebellar lobule VIIb to the left superior occipital gyrus, right precentral gyrus, and right postcentral gyrus were increased. Conclusions: The study establishes the cerebellum, particularly cerebellar lobule VIIb, as the multimodal hub for IGD. The cerebellum mediates the imbalance of multiple neural circuits in patients with IGD, including visual-spatial dissociation, executive control dysregulation, and positive feedback reinforcement of sensory-motor processes. This finding elucidates the distinctive unique neural characteristics of IGD and provides a precise positioning basis for the neuro-regulatory treatment of IGD.