Psoriatic arthritis (PsA) and rheumatoid arthritis (RA) are connective tissue autoimmune diseases. The present study aimed to check whether serum clusterin (CLU) concentration and its glycosylation pattern may be markers differentiating these diseases-blood sera of patients with PsA (n = 37), RA (n = 34), and healthy subjects (control, n = 21) were examined. CLU concentration was measured using the ELISA test. Glycosylation was analyzed using lectin-ELISA with sialo-specific lectins from Maackia amurensis (MAA) and Sambucus nigra (SNA) recognizing sialic acid (SA) α2,3- and α2,6-linked, respectively, and fucose-specific lectins from Lotus tetragonolobus (LTA), Ulex europaeus (UEA), and Lens culinaris (LCA) specific to fucose α1,3-linked, α1,2-linked, and core fucose, respectively. Significantly higher CLU concentrations were observed in the PsA than in the RA patients. The expression of α2,6-linked SA was significantly higher in the PsA and RA patients than in the control. The expression of SNA-reactive SA was visibly higher in the PsA compared to the RA and control group but insignificant. Negative significant correlations between CLU concentrations and its glycans reactivity with LTA and UEA were also observed. Significantly higher serum CLU concentration, accompanied by a high expression of SNA-reactive SA and a reduced degree of Lewis(x) and Lewis(y) antennary fucosylation, may constitute a promising panel of parameters differentiating PsA from RA.