Background: The occurrence of spontaneous bacterial peritonitis (SBP) is a significant complication among patients with cirrhosis, and has been linked to renal impairment. However, there have been no studies specifically focused on this problem. Objective: To determine the incidence and mortality rate of renal impairment after SBP in cirrhotic patients. Methodology: The study was carried out at the Department of Medicine at Liaquat University Hospital, Hyderabad, from January 2022 to July 2022, using a cross-sectional observational analysis. A sample of 291 cirrhotic patients was selected through non-probability consecutive sampling. SBP diagnosis was made when the ascitic fluid polymorphonuclear cell count was equal to or greater than 250 cells/mm³. Data was collected using a pre-structured, interview-based questionnaire containing inquiries about basic sociodemographic details, clinical examinations details, and particulars of laboratory investigation. The data was analyzed using and SPSS v. 26.0. Results: The study found that the incidence of SBP was 23.02%, with 30 episodes (45.52%) of SBP associated with renal impairment (transient in 50.82%, steady in 21.31%, and progressive in 27.87%). The mortality rate associated with progressive renal impairment was 100%, 53.85% with steady renal impairment, and 9.68% with transient renal impairment. The mortality rate in patients with renal impairment was significantly higher than in those without (44.26% vs. 8.06%). Conclusion: This study highlights the common occurrence of renal impairment after SBP among cirrhotic patients, and suggests that it is a poor prognostic factor for this infection. Keywords: Liver cirrhosis, incidence rate, mortality rate, renal impairment, spontaneous bacterial peritonitis.