A poly (methyl methacrylate) grafted guar gum/mineral substituted hydroxyapatite (PMMA-GG/M-HA) nanocomposite is reported to show enhanced physico-chemical and bio-chemical properties. This nanocomposite offers a possible bone cell integration around it with augmenting fresh bone development, thus declining the risk of cartilages' structural collapse. In this study, the as-fabricated nanocomposite was characterized by using physicochemical strategies. The cell-material boundary of the nanocomposite was observed in vitro with human osteoblast cells, and the cell replication was tested. The nanocomposite promoted the bone cell adhesion and proliferation, improved the mechanical strength and repressed the growth of bacterial cells. Keywords: Nanocomposite, Bacterial activity, Guar gum, Poly (methyl methacrylate), Osteoblast cell adhesion