Currently, traditional osteogenesis methods face significant challenges in terms of therapeutic efficiency and biocompatibility, particularly in the context of bone repair where higher precision and efficacy are required. In this study, we fabricated a novel composite scaffold composed of polycaprolactone (PCL), polydopamine (PDA), and iron oxide nanoparticles (IONPs) and investigated its osteogenic potential. The incorporation of IONPs imparts magnetic responsiveness to the scaffold, thereby enabling the application of an external magnetic field to stimulate osteogenesis. Characterization of the scaffold confirmed its structural integrity, porosity, and biocompatibility, whereas the inclusion of PDA improved its hydrophilicity and cell adhesion properties. In vitro studies demonstrated that an external magnetic field significantly enhanced cell proliferation, osteogenic differentiation, and mineral deposition of osteoprogenitor cells cultured on the scaffolds. Furthermore, in vivo evaluation revealed that when the scaffold was exposed to magnetic stimulation, bone regeneration was accelerated, and integration of the defect site was improved. The magnetic-field-mediated approach proposed in this study effectively enhanced the osteogenic rate by augmenting the magnetic responsiveness of IONPs and combining the biocompatibility and cell-adhesion-promoting functions of PCL/PDA. This method offers a more controllable and biologically responsive alternative strategy for bone tissue regeneration with considerable potential for clinical applications.