The role of platelet function indices—platelet count (PLT), mean platelet volume (MPV), platelet distribution width (PDW), plateletcrit (PCT), immature platelet fraction (IPF), and platelet mass index (PMI)—in psoriasis is uncertain. This systematic review and meta-analysis aimed to evaluate the association of these platelet biomarkers with both presence and severity of psoriasis. We searched MEDLINE (Ovid), Embase (Ovid), and the Cochrane Library from inception to November 2021. To evaluate the association of platelet function indices and psoriasis, we recorded mean differences (MD) and 95% confidence intervals (CI) as well as correlation coefficients (r) for each included study, and generated summary estimates using random-effects inverse-variance modelling. We screened 1,079 unique studies, and included 33 studies with 6724 patients in the quantitative analyses. Compared with controls, patients with psoriasis had higher PLT (MD 12.86 × 109/L, 95% CI 6.34–19.39,p< 0.001), MPV (MD 0.61fL, 95% CI 0.31–0.92,p< 0.001), and PCT (MD 0.05%, 95% CI 0.01–0.09,p= 0.010), but similar PDW (MD 0.16%, 95% CI -0.46–0.79,p= 0.610). Psoriasis Area and Severity Index (PASI) was weakly correlated with PLT (r 0.17, 95% CI 0.06–0.28,p= 0.003), MPV (r0.36, 95% CI 0.22–0.49,p< 0.001), and PDW (r0.17, 95% CI 0.08–0.26,p< 0.001). Study numbers were insufficient to judge the relationship of IPF and PMI with psoriasis presence, or PCT, IPF, and PMI with psoriasis severity. In summary, PLT, MPV, and PCT are significantly elevated in patients with psoriasis, and PLT, MPV, and PDW are weakly correlated with PASI. Future studies are needed to evaluate the independent diagnostic and prognostic potentials of these biomarkers in patients with psoriasis.Supplementary InformationThe online version contains supplementary material available at 10.1007/s10238-022-00820-5.