Postoperative peritonitis (POP) remains a severe complication of abdominal surgery, particularly in resource-limited settings, where delayed diagnosis and limited access to critical care contribute to poor outcomes. This study aimed to determine the prevalence, clinical characteristics, management modalities, and predictors of mortality among adults with postoperative peritonitis in Douala, Cameroon. We conducted a retrospective multicenter analytical study in two tertiary hospitals from January 2020 to December 2024. Adult patients diagnosed with postoperative peritonitis after abdominal or abdominopelvic surgery were included. Data were extracted from medical records and analyzed using univariate logistic regression. Among 4,763 laparotomies performed during the study period, 68 cases of postoperative peritonitis were identified, yielding a prevalence of 1.4%. After exclusion of incomplete records, 51 patients were included in the final analysis. The mean age was 35.4 ± 13.9 years, and women accounted for 82.4% of cases. Overall in-hospital mortality was 51.0%. The most frequent clinical features were abdominal pain (92.2%), abdominal guarding (86.3%), tachycardia (82.4%), and fever (76.5%). Deep suppuration (35.3%) and intestinal perforation (23.5%) were the most common intraoperative findings. Mortality was significantly associated with postoperative sepsis (OR 40.25, p<0.001), multiorgan failure (OR 37.84, p<0.001), vasopressor use (OR 17.60, p=0.002), prothrombin time <50% (OR 8.84, p=0.050), intensive care monitoring (OR 6.98, p=0.002), and blood transfusion (OR 4.55, p=0.020). Postoperative peritonitis remains an uncommon but highly lethal complication in our setting. Early diagnosis, prompt surgical source control, and