Psoriasis is an immune‐mediated chronic inflammatory skin disease. Although its pathogenesis is not fully understood, Th17 cells and the cytokines they produce, such as IL‐17, IL‐22 and IL‐23, play critical roles in the pathogenesis of psoriasis. Evidence has demonstrated that psoriasis has some common features, including immune responses (due to Th17 cells) and inflammatory cytokine profiles, with systematic diseases including inflammatory bowel diseases (IBDs) and obesity. Recently, studies have demonstrated that the gut microbiota plays a crucial role in host homoeostasis and immune response, particular in Th17 cells, but the role of the gut microbiota in psoriasis remains unclear. To study the relationship between gut microbiota and psoriasis, we analysed microbiota profiles in psoriasis using a 16S rDNA sequencing platform, and we found that the abundance of Akkermansia muciniphila was significantly reduced in patients with psoriasis. A. muciniphila is believed to have an important function in the pathogenesis of IBD and obesity; therefore, A. muciniphila, which is an indicator of health status, may be a key node for psoriasis as well as IBD and obesity. Taken together, our study identified that gut microbiota signature and function are significantly altered in the gut of patients with psoriasis, which provides a novel angle to understanding the pathogenesis of psoriasis.