Prostate cancer is a hormone-associated malignancy and is closely related to obesity in terms of epidemiology and molecular mechanisms. Adiponectin, an adipocytokine produced by adipokine and secreted by adipocyte, exhibits anti-inflammatory, insulin-sensitizing, anti-proliferation, and proapoptosis actions on various organs in an endocrine form. Obesity leads to a decrease in adiponectin level, which is closely associated with the occurrence of many tumors. Studies have showed that prostate cancer patients had lower serum adiponectin levels and decreased expression of adiponectin receptors in tumor tissues, which suggest that functional defects of adiponectin and its receptors may be relevant to the occurrence and development of prostate cancer. This paper reviews adiponectin and its receptors’ functions, signaling pathways, and roles in diagnosis, treatment, and prognosis of prostate cancer.