Sustained low-efficiency dialysis (SLED) is usually performed over 6–12 h among hemodynamically unstable patients. Conduction of 4-h SLED may spare time and manpower during hospitalization. Therefore, we conducted a retrospective observational study to explore the appropriateness and clinical outcomes of 4-h SLED among critically ill patients admitted to our center from 1/06/2016 to 1/06/2020. Renal parameters including blood urea nitrogen, serum creatinine, sodium, phosphorus, potassium, and bicarbonate were determined on the day of dialysis before SLED and within 24 h after SLED, and clinical outcomes including, acute kidney injury (AKI) recovery, in-hospital mortality, 30-day mortality, 180-day mortality, and re-admission with AKI, were evaluated. Of the 304 patients included, 69.4% were male. The majority of patients were from the Middle East (65.8%), followed by 28.6% from Asia. Four-hour SLED resulted in a significant improvement in the renal parameters. Recovery from AKI was observed in 25.4%, in-hospital mortality rate was 48.7%, while the 30- and 180-day mortality outcomes were 3.2 and 9.6%, respectively, and re-admission with AKI was observed in 16.9%. Our findings suggest that 4-h SLED significantly improved renal parameters and was associated with favorable clinical outcomes in terms of survival and AKI recovery, suggesting possible utilization of SLED shorter than 6 h in the acute settings to preserve time and manpower for procedures.