According to research, shock, the most common complication of extremely severe burns, is also the leading cause of mortality among patients with such burns. The case fatality rate reaches 83.45% when the total burn area exceeds 90%. The American Heart Association in 2020 recommended the intraosseous (IO) access after the peripheral access and prior to the central venous access when venous cannulation is either difficult or delayed. The use and experience with intraosseous infusion in extremely severe burns are still limited. We report efficacy and safety results from 19 burn patients treated with IO infusion between June 2020 and December 2022. In these patients, the mean injury time of burns was 1.55 ± 1.10 hours, the mean burn surface area was 86.24% ± 11.33%, the mean catheterization time was 49.68 ± 10.11 seconds, and the mean emergency retention time was 2.75 ± 1.74 hours, the mean actual fluid supplement amount was 5,533.68 ± 3,077.19 mL, the mean hourly urine volume of the patient was 93.31 ± 60.94 mL, the mean emergency detention time was 4.16 ± 2.97 hours, and the mean duration of hospitalization was 34.50 ± 25.38 days. The results demonstrated a clinically meaningful improvement and higher response rate vs peripheral venous cannulation and an acceptable safety profile in those patients.