In search of the ferromagnetic insulators for spintronic device applications, we have studied the electronic, optical and magnetic properties of La2CrNiO6 (LCNO) using the first principle density functional theory (DFT) and the Monte Carlo simulation technique. Firstly, we have adopted the sol-gel method for the preparation of LCNO and refined the X-ray diffracted value using the Fullprof suite under the Rietveld mechanism. The obtained orthorhombic Pbnm and cubic Fm-3m space groups are used as the input of the DFT calculations. Both the structures have shown the half metallicity and insulting bandgap towards the majority and minority spin direction, respectively. From the magnetic moment calculations, we have seen the low spin state of Ni3+, and the double exchange (DE) interaction are responsible for the ferromagnetic structure of LCNO. The optical dielectric constant is ten, and the refractive index is 3.2 for orthorhombic structure. The transition temperature (TC) is determined to be 110 K from the MCS study, which has well agreed with experimental value (111 K). The RCP value is determined to 12 J/kg with a 5 T applied field, which is good for magnetocaloric applications.