Acute respiratory distress syndrome (ARDS) is a life-threatening condition that commonly develops in patients with sepsis. Patients with ARDS require admission to intensive care and invasive mechanical ventilation. Vitamin B1 and C deficiencies have been reported in critically ill patients with sepsis. Vitamin B1 is involved in aerobic metabolism, and vitamin C has anti-inflammatory and anti-oxidative effects. The aim of this Korean retrospective cohort study was to evaluate the clinical impact of vitamin B1 and C supplementation in patients with sepsis-related ARDS. Patients with ARDS requiring invasive mechanical ventilation, admitted to an intensive care unit (ICU) were included in this study. Clinical outcomes were compared between patients administered with vitamin B1 (200 mg/day) and C (2 g/day) between June 2018-May 2019 (the supplementation group) and those who did not receive vitamin B1 and C administration between June 2017-May 2018 (the control group). Seventy-nine patients were included. Thirty-three patients received vitamin B1 and C, and 46 patients did not. There were no significant differences in the number of deaths between the patients who received vitamin B1 and C and those who did not. The mean number of days not requiring ICU admission or ventilation was greater in patients supplemented with vitamin B1 and C than that in the control patients, but the difference was not statistically significant. Steroid administration was more frequent in patients receiving vitamin B1 and C supplementation than in those without it. The authors concluded that Vitamin B1 and C supplementation at the doses used in this study did not reduce the death rates in ARDS patients.