Objective To evaluate the efficacy of vitamin C intravenous injection in the treatment of patients with sepsis. Methods PubMed, Embase, Scopus, Cochrane Library, and Clinical Trial databases were retrieved, with a retrieval period from database establishment to December 2022. English literatures on randomized controlled trial (RCT) of vitamin C intravenous injection for the treatment of sepsis or septic shock were collected. Meta-analysis was conducted using RevMan 5.3 software and Stata 15.0 software after literature screening, extraction, and evalua- tion of the bias risk included in the studies by two researchers independently. Results A total of 16 RCT studies involving 3 301 patients were included in the analysis. In terms of main outcomes, the 28-day mortality of patients in the vitamin C treatment group was slightly lower than that of the control group, but the difference was not statistically significant (RR=0.86, 95%CI [0.72-1.03], P=0.10; I²=44%, P=0.10). In terms of secondary outcomes, vitamin C intravenous injection can reduce the duration of vasoactive drug usage time (MD=-23.44, 95%CI [-30.53--16.35], P < 0.01; I²=0, P=0.97), but has no significant effect on the 90-day mortality, intensive care unit mortality, hospital mortality, duration of mechanical ventilation, difference in estimated sequential organ failure assessment score at 72 hour, length of stay in ICU, and total length of hospital stay of patients (P > 0.05). Conclusion Intravenous vitamin C injection can significantly reduce vasoactive drug usage time, but the available evidence is insufficient to support that intravenous vitamin C can improve the prognosis of patients with sepsis or septic shock. More high-quality, multicenter randomized controlled trial is needed to provide more substantial evidence about the efficacy of vitamin C in treating sepsis or septic shock.