Trauma is a serious public health problem, and abdominal injuries are among the leading causes of hospitalization after trauma. Therefore, this study aimed to determine the outcome of abdominal trauma and its predictors in patients who underwent laparotomy at Asella Referral and Teaching Hospital (ARTH), South Central Ethiopia. We conducted a retrospective institutional based cross-sectional study of patients who underwent laparotomy for abdominal trauma at ARTH from October 1, 2015, to September 30, 2020. Bivariate and multivariate logistic regressions were used to determine associations between independent factors and mortality due to abdominal trauma, and a value of <0.05 indicated statistical significance. Out of 139 patients, 110 (79.1%) were males and 88 (63.3%) aged <30 years old, with a mean age of 29 ± 15.73 years. The most common mechanism of injury was penetrating trauma, which accounted for 94 (67.6%) patients. The mortality rate was 21 (15.1%). Factors such as blunt mechanism of injury (95% CI: AOR: 3.36, 1.24-9.09), SBP < 90 mmHg at presentation (95% CI: AOR = 9.37, 3.28-26.80), time >6 hours from trauma to admission (95% CI: AOR: 5.44, 1.78-16.63), unstable intraoperative patient condition (95% CI: AOR = 8.82, 3.05-25.52), and patients who need blood transfusion (95% CI: AOR: 6.63, 1.92-22.91) were significantly associated with mortality. The mortality rate of abdominal trauma patients who underwent laparotomy was high. Therefore, healthcare providers should provide priority for traumatic patients as prolonged waiting time to get healthcare results in poor outcomes for the patients.