CytoSorb is a hemoadsorptive column used to remove high concentrations of proinflammatory cytokines in septic shock. Data on CytoSorb application in acute-on-chronic liver failure (ACLF) is lacking. This retrospective observational study analyzed 21 ACLF patients admitted to ICUs at the Vienna General Hospital who received CytoSorb adsorber therapy between 2017 and 2023. Median ICU length of stay was 8days (IQR: 3-13), the ICU survival rate was 23.8% (n = 5). Significant decreases in bilirubin (median peak: 20.7mg/dL to median post-treatment: 10.8mg/dL; - 47.8%; p < 0.001), procalcitonin (1.34 to 0.74pg/mL; - 44.6%; p < 0.001), interleukin-6 (385 to 131ng/mL; - 66.0%; p = 0.0182)-but also of platelets (72 to 31 G/L; - 56.9%; p = 0.0014) and fibrinogen (230 to 154mg/dL; - 33.0%; p = 0.0297) were detected. ICU survivors had a trend towards a stronger relative decrease in bilirubin (- 76.1% vs. - 48.2%), procalcitonin (- 90.6% vs. - 23.5%), and IL-6 (- 54.6% vs. - 17.8%) upon CytoSorb treatment. Moreover, no serious CytoSorb-attributed complications were detected. In conclusion, use of CytoSorb adsorber in ACLF patients results in a significant decrease in bilirubin and proinflammatory cytokines, while platelets and fibrinogen were also lowered. Prospective trials are warranted to investigate the impact of CytoSorb on clinical outcomes of ACLF patients with high proinflammatory cytokine levels.