Prostaglandins (PGs) are lipid-derived autacoids that are synthesized from arachidonic acid by the action of cyclooxygenases and PG terminal synthases. PGs consist of PGD, PGE, PGF, prostacyclin (PGI), and thromboxane A, which act through G protein-coupled receptors. PGs sustain homeostatic functions and exert a variety of pathophysiological roles to regulate the development of various diseases such as obesity and dyslipidemia. Adipocytes (fat cells) have the unique capacity to accumulate large amounts of lipids as energy source in lipid droplets. Adipogenesis is the process of differentiation from preadipocytes to mature adipocytes, which is regulated by various adipogenic transcription factors. Obesity is defined as an abnormal increase in adipose tissue mass and is considered to be a risk factor for the development of lifestyle-related diseases including cardiovascular disease, hyperlipidemia, and type 2 diabetes mellitus. This review summarizes insights into the roles of PGD, PGF, and their synthases in the regulation of adipogenesis and obesity.