Background and Aims: Although global birth outcomes have improved considerably in the last 40 years, there are disparities in underdeveloped countries, particularly Ethiopia, remain significant. However, there was inadequate data about the adverse outcome in the study area. This study aimed to assess the proportion and associated factors of adverse birth outcomes among women who gave birth at South Gondar Health Institutions in 2021. Methods: The multistage sampling technique was used to select 928 participants from December 15, 2020, to February 2, 2021. Face-to-face intervieweradministered questionnaires and card reviews were used. The data were entered into Epi-Data 4.2 and analyzed by SPSS version 23. The statistical association was determined using the odds ratio, 95% confidence interval (CI), and a p-value of less than 0.05. Results:The proportion of fetal and maternal adverse birth outcomes were 26.7%, and 12.3%, respectively. Previous history of abortion (adjusted odds ratio [AOR] = 2.10, 95% CI = 1.31, 3.66), antenatal care (ANC) follow up (AOR = 3.30, 95% CI = 1.67, 6.58), premature rupture of membrane and hyperemesis (AOR = 3.27, 95% CI = 1.55, 5.89), obstructed labor and meconium-stained amniotic fluid (AOR = 2.31, 95% CI = 1.21, 4.39), and cesarean birth (AOR = 0.50, 95% CI = 0.28, 0.88) were significantly associated fetal adverse birth outcome. Antepartum hemorrhage during the latest pregnancy was associated with maternal adverse birth outcomes (AOR = 1.87, 95% CI = 1.03, 3.38). Conclusion:The proportion of adverse birth outcomes in this study was high.Provide community-based health information about ANC follow-up, and community mobilization to reduce abortion. Appropriately manage premature rapture of the membrane after hospital admission.