PsA is an axial and/or peripheral inflammatory arthritis associated with psoriasis, included in the group of spondylarthritides. It has been suggested that PsA could be a systemic disease, involving even coronary arteries and the heart. An increased prevalence of vascular risk factors has been found in PsA subjects as compared with the general population and psoriatic subjects. Moreover, PsA patients exhibit an increased prevalence of liver steatosis, a marker of metabolic syndrome, and of obesity. Interestingly, many reports demonstrate that adipose tissue is metabolically active, representing a source of inflammatory mediators, known as adipokines. The latter include TNF-α, macrophage chemoattractant protein-1, plasminogen activator inhibitor-1 (PAI-1), IL-6, leptin and adiponectin, leading to a pro-inflammatory status in obese subjects. This evidence supports the idea of obesity as a low-grade inflammatory disease. Accordingly, obesity might be associated with some rheumatic diseases. In particular, it seems to affect several features of PsA, such as its development, cardiovascular risk and clinical outcome. Recent data suggest that increased BMI in early adulthood increases the risk of PsA development in psoriatic patients, supporting a link between fat-mediated inflammation and joint involvement. Obesity may represent an additive cardio-metabolic risk factor in PsA subjects. Abdominal obesity may also determine an increased risk of not achieving minimal disease activity in PsA patients, highlighting the role of abdominal fat accumulation as a negative predictor of good clinical response to biologic agents. This review assesses the relationship between obesity and PsA according to the available literature.