The increasing use of extended criteria donor (ECD) livers, including donation after circulatory death (DCD) grafts, necessitates improved preservation and viability assessment methods. Ex-situ liver machine perfusion (MP) techniques, such as dual hypothermic oxygenated machine perfusion (DHOPE) and normothermic machine perfusion (NMP), are critical for preservation, preconditioning, and viability assessment. Controlled oxygenated rewarming (COR) following static cold storage (SCS) can be utilized to precondition grafts before transplantation by rewarming to subnormothermia or transition grafts from DHOPE to NMP for viability assessment. Both strategies have shown significant benefits in both experimental and clinical settings, including improved graft function and reduced cellular damage. COR involves optimizing oxygen supply to the graft by ensuring a rise in vascular flows and maintaining adequate oxygenation of the perfusate during perfusion. The rewarming rate impacts outcomes, with slower rates improving vascular resistance and minimizing cellular injury. The subsequent restoration of metabolic activity during COR is marked by lactate clearance and resumed bile production. COR aims to reduce rewarming injury by controlling the imminent temperature transition to normothermia by facilitating a rise in oxygen supply parallel to the rise in metabolic demand during the rewarming process. Protocols utilizing COR have demonstrated excellent outcomes in clinical practice.