To discover novel biomarkers of psoriasis, a target-specific antibody array screening of serum samples from psoriasis patients was initially performed. The results revealed that vascular endothelial growth factor receptor 3 (VEGFR-3) was significantly elevated in the sera of psoriasis patients, compared to healthy controls. Next, ELISA validation studies in a larger cohort of psoriasis patients (N = 73) were conducted, which confirmed that serum VEGFR-3 was indeed significantly increased in patients with psoriasis compared to healthy controls (P< 0.001). Furthermore, receiver operating characteristic curve analysis demonstrated that serum VEGFR-3 exhibited potential in distinguishing healthy controls from psoriasis patients: area under the curve = 0.85, P < 0.001. In addition, serum levels of VEGFR-3 were correlated with Psoriasis Area Severity Index scores (R = 0.32, P = 0.008) in psoriasis patients. Interestingly, serum VEGFR-3 levels were significantly elevated in psoriatic arthritis compared to non-psoriatic arthritis (P = 0.026). A pilot longitudinal study demonstrated that serum levels of VEGFR-3 could reflect disease progression in psoriasis. Collectively, serum VEGFR-3 may have a clinical value in monitoring disease activity of psoriasis.