AbstractFirsocostat is an oral, liver‐targeted inhibitor of acetyl‐coenzyme A carboxylase in development for the treatment of metabolic dysfunction‐associated steatohepatitis. Hepatic organic anion transporting polypeptides play a significant role in the disposition of firsocostat with minimal contributions from uridine diphospho‐glucuronosyltransferase and cytochrome P450 3A enzymes. This phase 1 study evaluated the pharmacokinetics and safety of firsocostat in participants with mild, moderate, or severe hepatic impairment. Participants with stable mild, moderate, or severe hepatic impairment (Child–Pugh A, B, or C, respectively [n = 10 per cohort]) and healthy matched controls with normal hepatic function (n = 10 per cohort) received a single oral dose of firsocostat (20 mg for mild and moderate hepatic impairment; 5 mg for severe hepatic impairment) with intensive pharmacokinetic sampling over 96 h. Safety was monitored throughout the study. Firsocostat plasma exposure (AUC_inf) was 83%, 8.7‐fold, and 30‐fold higher in participants with mild, moderate, and severe hepatic impairment, respectively, relative to matched controls. Firsocostat was generally well tolerated, and all reported adverse events were mild in nature. Dose adjustment is not necessary for the administration of firsocostat in patients with mild hepatic impairment. However, based on the observed increases in firsocostat exposure, dose adjustment should be considered for patients with moderate or severe hepatic impairment, and additional safety and efficacy data from future clinical trials will further inform dose adjustment.