The clinical efficacy and safety of ertapenem use in patients undergoing renal replacement therapies (RRT) are not well-documented. Therefore, we aimed to investigate the safety and efficacy of ertapenem in patients with sepsis secondary to Enterobacterales who are undergoing RRT. A retrospective cohort study was conducted on patients who met the inclusion criteria at our hospital between May 2015 and December 2021. The primary endpoint was 30-day mortality. Secondary endpoints included clinical cure, microbiologic cure, recurrence rate, and incidence of seizures. During the study period, 158 patients met the inclusion criteria. Of these, 86 were male (54.4%), the mean age was 66.4 ± 13.8 years, and the mean weight was 77 ± 22.4 kg. The most common diagnosis was bacteremia in 48 (30.4%) subjects, followed by urinary tract infection in 39 (24.7%) subjects, and pneumonia in 35 (22.2%) patients. The most isolated pathogens were Escherichia coli, followed by Klebsiella species. The median ertapenem dose was 0.5 g intravenously (IV) daily in those who received intermittent hemodialysis (IHD) and 1 g IV daily for those who received continuous veno-venous hemofiltration (CVVH). The 30-day mortality rate was 24%, the clinical cure rate was 89.2%, the microbiologic cure rate was 82%, the 30-day recurrence rate was 41.1%, and the incidence of seizures was 2.5%. Multivariate logistic regression analysis indicated that age (OR 1.04 [95% CI: 1.003-1.075]), being critically ill at therapy initiation (OR 2.9 [95% CI: 1.1-7.5]), and Enterobacterales other than Klebsiella species and Escherichia coli (OR 3.8 [95% CI: 1.1-12.5]) were significant independent risk factors associated with mortality in this population. Ertapenem dose was not associated with mortality. Our findings suggest that the commonly used doses of ertapenem in patients undergoing IHD and CVVH are clinically effective but may pose a higher risk of seizures. A comprehensive pharmacokinetic study is needed to determine the most effective and safe dose for this population.