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Abstract Background Metabolic syndrome (MetS) is a risk factor in surgery. MetS can progress to metabolic (dysfunction)-associated fatty liver disease (MAFLD), a vast-growing etiology of primary liver tumors which are major indications for liver surgery. The aim of this meta-analysis was to investigate the impact of MetS on complications and long-term outcomes after hepatectomy. Methods The protocol for this meta-analysis was registered at PROSPERO prior to data extraction. MEDLINE, Web of Science, and Cochrane Library were searched for publications on liver resections and MetS. Comparative studies were included. Outcomes encompassed postoperative complications, mortality, and long-term oncologic status. Data were pooled as odds ratio (OR) with a random-effects model. Risk of bias was assessed using the Quality in Prognostic Studies tool (QUIPS), and the certainty of the evidence was evaluated with GRADE. Subgroup analyses for patients with histopathologically confirmed non-alcoholic fatty liver disease (NAFLD) versus controls were performed. Results The meta-analyses included fifteen comparative studies. Patients with MetS suffered significantly more overall complications (OR 1.55; 95% CI [1.05; 2.29]; p=0.03), major complications (OR 1.97 95% CI [1.13; 3.43]; p=0.02; I 2=62%), postoperative hemorrhages (OR 1.76; 95% CI [1.23; 2.50]; p=0.01) and infections (OR 1.63; 95% CI [1.03; 2.57]; p=0.04). There were no significant differences in mortality, recurrence, 1- or 5-year overall or recurrence-free survivals. Patients with histologically confirmed NAFLD did not have significantly more overall complications; however, PHLF rates were increased (OR 4.87; 95% CI [1.22; 19.47]; p=0.04). Recurrence and survival outcomes did not differ significantly. The certainty of the evidence for each outcome ranged from low to very low. Conclusion Patients with MetS that undergo liver surgery suffer more complications, such as postoperative hemorrhage and infection but not liver-specific complications—PHLF and biliary leakage. Histologically confirmed NAFLD is associated with significantly higher PHLF rates, yet, survivals of these patients are similar to patients without the MetS. Further studies should focus on identifying the tipping point for increased risk in patients with MetS-associated liver disease, as well as reliable markers of MAFLD stages and early markers of PHLF. Trial registration PROSPERO Nr: CRD42021253768