The study aimed to determine the burden of critical illness, treatment outcomes, and availability of Essential Emergency and Critical Care (EECC) in 12 Ethiopian hospitals. Of 1,077 hospitalized patients, 221 (20.5%) were critically ill, with the majority (62%) managed in general wards. Seven-day in-hospital mortality was 14.0% among critically ill patients compared to 2.8% in non-critically ill patients. Only 1.8% of critically ill patients received all indicated treatments. The median availability of EECC resources in hospitals was 70.9%, with no hospital fully equipped across all domains. Qualitative analysis identified seven major barriers including challenges in early identification, resource constraints, knowledge gaps, and organizational obstacles. The study emphasizes the urgent need to strengthen decentralized EECC through training, resource provision, and addressing systemic barriers to improve outcomes in resource-limited settings.