Platinum nanoparticles (PtNP) exhibit remarkable antioxidant activity. There is growing evidence concerning a positive relationship between oxidative stress and bone loss, suggesting that PtNP could protect against bone loss by modulating oxidative stress. Intragastric administration of PtNP reduced ovariectomy (OVX)-induced bone loss with a decreased level of activity and number of osteoclast (OC) in vivo. PtNP inhibited OC formation by impairing the receptor activator of nuclear factor-${kappa}B$ ligand (RANKL) signaling. This impairment was due to a decreased activation of nuclear factor-${kappa}B$ and a reduced level of nuclear factor in activated T-cells, cytoplasmic 1 (NFAT2). PtNP lowered RANKL-induced long lasting reactive oxygen species as well as intracellular concentrations of $Ca^{2+}$ oscillation. Our data clearly highlight the potential of PtNP for the amelioration of bone loss after estrogen deficiency by attenuated OC formation.