Introduction: Acute transfusion reactions are adverse events occurring within 24 hrs of transfusion and cause simple-to-severe complications. They may vary with the blood component transfused and recipient factors. In Ethiopia, there is a limited evidence about the incidence and associated factors of transfusion reactions. Objective: To determine the proportion of acute transfusion reactions and associated factors among adult transfused patients. Methods: A total of 384 study participants were included in the study. Structured questionnaires were used for socio-demographic and past medical history data collection. Vital signs were measured as a baseline for every study participants and monitored and followed for 24 hrs. Laboratory tests like complete blood count, direct anti-human globulin test and urine hemoglobin were done as a baseline for suspected patients. Cross-match, blood grouping, and blood culture for patients and donors sample were also done for suspected patients. Descriptive statistics, bivariable and multivariable binary logistic regression were analyzed using SPSS version 20. P-value of <0.05 in the multivariable model was considered as statistically significant. Results: Acute transfusion reactions were observed in 5.2% of patients. Of total cases of acute transfusion reaction, the majority developed allergic reactions (65%) and febrile non-hemolytic transfusion reaction (30%). It was significantly associated with transfusion history (AOR=3.4; 95% CI: 1.2-9.7), abortion history (AOR=5.0; 95% CI: 1.5-16.4), longer blood storage time (AOR=5.1; 95% CI: 1.7-15.2) and receiving three or more unit of blood (AOR= 4.1; 95% CI: 1.5-11.2). Conclusion: Acute transfusion reactions were observed in 5.2% of patients (allergic reactions (65%), febrile non-hemolytic transfusion reaction (30%) and alloimmunization (5%)). Patients with a history of transfusion, abortion, transfused with blood stored ≥14 days and multi-transfused patients should be closely monitored.