The aim of the study was to evaluate the influence of metabolic syndrome (MetS) on achieving minimal disease activity (MDA) in psoriatic arthritis (PsA) patients treated with anti-tumor necrosis factor (TNF)-α with a follow-up period of 24 months. A cohort of PsA patients was assessed at the University Federico II of Naples and at University of Padova. For the aim of the present study, patients' data were collected at baseline (T0), at 12 months (T1) and at 24 months (T2). Assessment of metabolic and disease activity parameters was performed at each visit. The NCEP-ACT III criteria were used to identify subjects with MetS and the MDA criteria to evaluate the disease activity. On the basis of the exclusion and inclusion criteria, 330 subjects were included in the study; 134 patients (40.7%) were classified as not having MetS and 196 (59.3%) as having MetS. An inverse association was found between presence of metabolic syndrome and the probability of achieving MDA. Univariate analysis indicated that patients with metabolic syndrome were less likely to achieve MDA than patients without metabolic syndrome (OR 0.45, p < 0.001). This inverse association remained statistically significant in the multivariate regression model (OR 0.56, p < 0.001). Metabolic syndrome is associated with a lower probability of achieving MDA in PsA patients in therapy with anti-TNF-α.