Background: Maternal death, the most catastrophic end, is frequently described as just “tip of the iceberg” whereas severe maternal morbidity (near miss) as the “base”. Regardless of the efforts in maternal health care; maternal morbidity, disabilities, and deaths remain a major public health problem in developing countries including Ethiopia. Furthermore, in Ethiopia still, there is limited verification on the predictor of severe maternal morbidity. Thus, the main objective of this study was to assess determinants of maternal near miss among women admitted in public hospitals of West Arsi zone, Ethiopia. Methodology: A facility-based unmatched case-control study was conducted from 1 st March to 30th April 2019. Cases were recruited sequentially as they present whereas controls by systematic sampling method with a total sample of 321 participants (80 cases and 241 controls). Cases were women admitted to hospitals during pregnancy, delivery or within 42 days of termination of pregnancy and fulfilled at least one of the maternal near-miss validated disease-specific criteria, while controls were women admitted for normal labor and gave birth by normal vaginal delivery. Data were entered and cleaned using Epi data 3.1; analyzed by SPSS 20. Logistic regression was used to determine the effect of various factors on the outcome variable. Result: In this study, the major severe maternal near-miss morbidities were severe obstetric hemorrhage (32.5%), pregnancy-induced hypertensive disorders (31.3%) and obstructed labor (26.3%); followed by 6.3% and 3.8% of severe anemia and pregnancy-induced sepsis, respectively. The odds of maternal near miss was statistically significantly associated with women’s lack of formal education (AOR = 2.24, 95% CI 1.17, 4.31), not attending antenatal care (AOR = 3.71 95% CI 1.10, 12.76), having prior history of cesarean section (AOR = 3.53, 95% CI 1.49, 8.36), any pre-existing chronic medical disorder (AOR = 2.04, 95% CI 1.11, 3.78) and having experienced first delay (AOR = 5.74, 95% CI 2.93, 11.2). Conclusion: Maternal education, antenatal care, chronic medical disorders, previous cesarean section and first delay of obstetric care seeking were identified determinants of maternal near miss morbidity: besides implying the need for multidisciplinary works to forestall factor escalating severe maternal complications subsequently maternal mortality.