Background: Biomarkers associated with disease severity and comorbid metabolic syndrome (MetS) in patients with hidradenitis suppurativa (HS) are lacking. Objective: To identify biomarkers associated with disease severity and comorbid MetS in patients with HS. Methods: Data on hospital outpatients with HS were obtained through clinical examination and interviews. Indicators of systemic inflammation; C-reactive protein (CRP), erythrocyte sedimentation-rate (ESR), neutrophil/lymphocyte-ratio (NLR), platelet/lymphocyte-ratio (PLR), monocyte/lymphocyte-ratio (MLR), platelet/neutrophil-ratio (PNR), pan-immune-inflammation-value (PIV), and systemic-immune-inflammatory-index (SII), were calculated from blood samples. Results: Seven hundred patients were included; of those 444 (63.4%) and 256 (36.6%) were female and male, respectively, with a median age of 38.3 years (IQR = 27.9-51.0). Increasing CRP, ESR, NLR, PIV, and SII (P < .001) were significantly associated with increasing Hurley-stage and international hidradenitis suppurativa severity score system 4 (IHS4)-score in adjusted analysis. A doubling in CRP (OR 1.59 (1.36-1.85), P < .001), ESR (OR 1.39 (1.17-1.66), P < .001) and PIV (OR 1.41 (1.12-1.77) P = .002) was associated with MetS in adjusted analysis. ESR was the best estimator for severe IHS4-score (AUC = 0.72 (0.66-0.77), P < .001) and Hurley III (AUC = 0.79 (0.73-0.85), P < .001) whereas CRP was best for MetS (AUC = 0.67 (0.62-0.72), P < .001). Limitations: Patients in a hospital setting tend to have more severe disease. Conclusion: Biomarkers like CRP, ESR, and PIV measuring systemic inflammation were associated with disease severity and comorbid MetS in patients with HS.