Periodontal diseases occur through bacterial infection in the oral cavity, which can cause alveolar bone loss. Several efforts have been made to reconstruct alveolar bone, such as grafting bone substitutes and 3D-printed scaffolds. Poly(ε-caprolactone) (PCL) is biocompatible and biodegradable, thus demonstrating its potential as a biomaterial substitute; however, it is difficult for cells to adhere to PCL because of its strong hydrophobicity. Therefore, its use as a biomaterial has limitations. In this study, we used graphene oxide (GO) as a coating material to promote the osteogenic differentiation ability of PCL scaffolds. First, 3D-printed PCL scaffolds were fabricated, and the oxygen plasma treatment and coating conditions were established according to the concentration of GO. The physical and chemical properties of the prepared scaffolds were evaluated through water contact angle analysis, Raman spectroscopy, and image analysis. In addition, the adhesion and proliferation of periodontal ligament stem cells (PDLSCs) on the GO scaffolds were assessed via the water-soluble tetrazolium salt-1 (WST-1) assay, and the osteogenic differentiation ability was evaluated through alizarin red S staining. The results confirmed that the cell proliferation and osteogenic differentiation of the PDLSCs were enhanced in the scaffolds coated with oxygen plasma and GO. In conclusion, the plasma-treated GO-coating method that we developed can be used to promote the cell proliferation and osteogenic differentiation of the scaffolds.