This randomized controlled trial investigated dexmedetomidine’s (DEX) efficacy as a cardioprotective agent in children with classic tetralogy of Fallot undergoing corrective surgery in Indonesia. Administering DEX in the cardiopulmonary bypass solution significantly reduced troponin I levels, interleukin-6, and lactate levels postoperatively, indicating reduced cardiac injury and inflammation. It also improved cardiac output and reduced the need for vasoactive drugs in intensive care, although it did not significantly impact ventilation duration, ICU stay, or mortality. These findings suggest DEX is an effective cardioprotective agent in pediatric cardiac surgery.