The current research investigates the effect of reinforcing magnesium oxide nanoparticles (n-MgO) on the physico-chemical, mechanical, and cellular activities of our previously developed three-dimensional printed sodium alginate (SA)/silk fibroin (SF)/polyvinyl alcohol (PVA)/nano-hydroxyapatite (HA) composite scaffold with optimized composition containing SA/SF:70:30 (v/v) with 3wt% PVA tri-polymer ratio and 1.5wt% n-HA designated as SA ₇₀/SF ₃₀/PVA ₃/n-HA _1.5 proven to be a suitable matrix for bone tissue engineering application. The chemically synthesized n-MgO was incorporated at two different concentrations of 0.5 wt% and 1 wt% into the SA/SF/PVA/n-HA solution and the resulting composite bioinks were used to fabricate 3D printed scaffolds as SA ₇₀/SF ₃₀/PVA ₃/n-HA _1.5/n-MgO _0.5 and SA ₇₀/SF ₃₀/PVA ₃/n-HA _1.5/n-MgO ₁. The scaffolds possess a microfibrous interconnected porous network with desired pore sizes ranging from 384±74µm and 362±57µm. The tensile strength measuring 4.09±1.13 MPa and 5.08±1.14 MPa for SA ₇₀/SF ₃₀/PVA ₃/n-HA _1.5/n-MgO _0.5 and SA ₇₀/SF ₃₀/PVA ₃/n-HA _1.5/n-MgO ₁ was enhanced upon reinforcing n-MgO matching with the mechanical strength of a cancellous bone and suitable for bone tissue regeneration under the load condition. In-vitro cell studies performed with HOS cells have shown the cytocompatible properties of the SA ₇₀/SF ₃₀/PVA ₃/n-HA _1.5/n-MgO ₁ scaffold. The up-regulation of ALP activity indicated that the scaffold might support superior osteoblast function and differentiation.