The present work is focused on synthesis of MgO nanoparticles by using green method. MgO nanoparticles were prepared by using black grapes. In this green synthesis method, Magnesium nitrate is used as a precursor. The synthesised MgO nanopowder is analysed by Powder XRD, TEM with SAED, Vibrational Sample Magnetometer (VSM) and photocatalytic studies. Powder XRD studies shows that the average particle size was 11.18 nm. The TEM studies confirm the morphology, crystallinity, and particle size of the synthesised MgO nanoparticles. The magnetic properties of MgO nanoparticle is analysed by using vibrational sample magnetometer. The photocatalytic degradation of Rhodamine B-dye is evaluated using the as-prepared MgO nanoparticles under visible light.