Early-stage bone infections are difficult to treat because of antibiotic resistance and limited regeneration of irregular bone defects. We developed a three-dimensional printed hydrogel scaffold combining a mechanically reinforced, electrically conductive nanomaterial with a bioactive polyamine. The scaffold enabled near-infrared–responsive photothermal antibacterial activity and reduced excessive reactive oxygen species, providing a favorable regenerative microenvironment. The bioactive component promoted osteogenic differentiation and angiogenesis while maintaining cellular homeostasis. The scaffold showed excellent biocompatibility with adipose-derived stem cells and enhanced osteogenic differentiation through synergistic effects. In a rat calvarial defect model, significant new bone formation was observed, demonstrating effective in vivo bone regeneration. This hydrogel scaffold offers a promising strategy for infected bone defect repair.