This experimental study aimed to create a prefabricated vascularized bone graft using the interconnected porous coralline hydroxyapatite ceramic by combining vascular bundle implantation, mesenchymal stem cells, and hyperbaric oxygen therapy (HBOT) administration in a rat model. Forty-five male Sprague-Dawley rats were divided into three groups, each containing 15 rats. The hydroxyapatite ceramics were vascularized by the superficial inferior epigastric artery and vein in all groups. These vessels passed through the hole of the hydroxyapatite blocks. In Group 2, mesenchymal stem cells were administered into the hydroxyapatite. In Group 3, both mesenchymal stem cells and HBOT were administered. The presence and density of any new bone formation and neovascularization were evaluated by radiography, microangiography, scintigraphy, biochemical analysis, and histomorphometry. Neovascularization and bone formation were significantly greater in Group 3, in which both mesenchymal stem cells and HBOT were applied, than the other groups. HBOT enhances neovascularization and osteogenesis, thus HBOT can provide optimal and faster prefabrication of a vascularized bone graft.