Background and Aims Human immunodeficiency virus (HIV)–hepatitis C virus (HCV)–coinfected patients are at high risk of metabolic complications and liver‐related events, which are both associated with hepatic steatosis and its progressive form, nonalcoholic steatohepatitis, a known risk factor for mortality. The fatty liver index (FLI), a noninvasive steatosis biomarker, has recently drawn attention for its clinical prognostic value, although its capacity to predict mortality risk in HIV–HCV‐coinfected patients has never been investigated. Using a Cox proportional hazards model for mortality from all causes, with data from the French National Agency for Research on Aids and Viral Hepatitis CO13 HEPAVIH cohort (983 patients, 4,432 visits), we tested whether elevated FLI (≥60) was associated with all‐cause mortality. Approach and Results After multiple adjustment, individuals with FLI ≥ 60 had almost double the risk of all‐cause mortality (adjusted hazard ratio [95% confidence interval], 1.91 [1.17‐3.12], P = 0.009), independently of the following factors: HCV cure (0.21 [0.07‐0.61], P = 0.004), advanced fibrosis (1.77 [1.00‐3.14], P = 0.05), history of hepatocellular carcinoma and/or liver transplantation (7.74 [3.82‐15.69], P < 10−3), history of indirect clinical signs of cirrhosis (2.80 [1.22‐6.41], P = 0.015), and HIV Centers for Disease Control and Prevention clinical stage C (2.88 [1.74‐4.79], P < 10−3). Conclusions An elevated FLI (≥60) is a risk factor for all‐cause mortality in HIV–HCV‐coinfected patients independently of liver fibrosis and HCV cure. In the present era of nearly 100% HCV cure rates thanks to direct‐acting antivirals, these findings encourage the more systematic use of noninvasive steatosis biomarkers to help identify coinfected patients with higher mortality risk.< Réduire