Preclinical and clinical data suggest that fibroblast growth factor 21 (FGF21) is anti-fibrotic, improves metabolic status and has potential to treat non-alcoholic steatohepatitis (NASH). We assessed the safety and efficacy of efruxifermin, a long-acting Fc-FGF21 fusion protein, for the treatment of NASH. BALANCED was a randomized, placebo-controlled study in patients with NASH conducted at 27 centers in the United States (ClinicalTrials.gov NCT03976401). Eighty patients, stratified by hepatic fat fraction (HFF) and fibrosis stage, were randomized using a centrally administered minimization algorithm 1:1:1:1 to receive placebo (n = 21) or efruxifermin 28 mg (n = 19), efruxifermin 50 mg (n = 20) or efruxifermin 70 mg (n = 20) via weekly subcutaneous injection for 16 weeks. The primary endpoint—absolute change from baseline in HFF measured as magnetic resonance imaging–proton density fat fraction at week 12—was met. For the full analysis set, the least squares mean absolute changes (one-sided 97.5% confidence interval) from baseline in HFF were −12.3% (−infinity (−inf), −10.3), −13.4% (−inf, −11.4) and −14.1% (−inf, −12.1) in the 28-, 50- and 70-mg groups, respectively, versus 0.3% (−inf, 1.6) in the placebo group, with statistically significant differences between efruxifermin groups and placebo (P < 0.0001 each). Overall, 70 of 79 patients who received the study drug (89%) experienced at least one treatment-emergent adverse event (TEAE), with the majority grade 1–2 (64 (81%)), five (6%) grade 3 and one grade 4. The most commonly reported drug-related TEAEs were grade 1–2 gastrointestinal (36 (46%)). Treatment with efruxifermin significantly reduced HFF in patients with F1–F3 stage NASH, with an acceptable safety profile.