Although the effect of levocarnitine (L-carnitine) on hyperammonemia has been reported in patients with liver cirrhosis (LC), its effect on sarcopenia remains to be elucidated. We assessed the effects of L-carnitine on sarcopenia in patients with LC. We retrospectively evaluated 52 patients with LC who were treated with L-carnitine for more than 3 months between February 2013 and June 2017. Computed tomography was used to measure the cross-sectional area of the skeletal muscles at the level of the third lumbar vertebra. The relative change in skeletal muscle index (SMI) per year (ΔSMI/year) was computed in each patient. We evaluated the relationship between ΔSMI/year and various parameters, such as age, sex, liver functional reserve, and dose of L-carnitine. The median ΔSMI/year for all patients was -0.22%. The ΔSMI/year values in Child-Pugh classes A, B, and C were not significantly different among the three groups. There was no significant relationship between ΔSMI/year and sex, age, body mass index, and sarcopenia. Multivariate analysis showed that only a high dose of L-carnitine (odds ratio [OR], 4.812; 95% confidence interval [CI], 1.233-18.784; P = 0.024) was associated with increased muscle mass. The L-carnitine high-dose group included a significantly larger number of patients with increased muscle mass compared with the low-dose group (OR, 3.568; 95% CI, 1.138-11.185; P = 0.027). Administration of L-carnitine led to a significant and gradual reduction in serum ammonia levels. Conclusion: L-carnitine seems to suppress the progression of sarcopenia dose dependently, and this was noted to be associated with the improvement of hyperammonemia in patients with LC.