The prevalence of obesity and related disorders has vastly increased throughout the world and prevention of such circumstances thus represents a major challenge. Here, it has been shown that one protein-bound β-glucan (PBG) from the edible mushroom Coriolus versicolor can be a potent anti-obesity component.PBG can reduce obesity and metabolic inflammation in mice fed with a high-fat diet (HFD). Gut microbiota analysis reveals that PBG markedly increases the abundance of Akkermansia muciniphila, although it does not rescue HFD-induced change in the Firmicutes to Bacteroidetes ratio. It appears that PBG alters host physiology and creates an intestinal microenvironment favorable for A. muciniphila colonization. Fecal transplants from PBG-treated animals in part reduce obesity in recipient HFD-fed mice. Further, PBG is shown to upregulate expression of a set of genes related to host metabolism in microbiota-depleted mice.The data highlight that PBG may exert its anti-obesity effects through a mirobiota-dependent (richness of specific microbiota) and -independent (modulation of host metabolism) manner. The fact that C. versicolor PBGs are approved oral immune boosters in cancers and chronic hepatitis with well-established safety profiles may accelerate PBG as a novel use for obesity treatment.