<p>Electroless nickel plating is widely utilized as a surface coating material in various industries including aerospace and automotives to enhance the mechanical strength and corrosion resistance of materials. When applied to materials with poor machinability, electroless nickel plating enables the production of high-performance optical components due to its excellent ultra-precision machining characteristics. However, despite ongoing research into the application of electroless nickel plating for space optical systems, its practical use has remained limited. This is primarily due to the low machinability of the material during the final process of magnetorheological finishing (MRF). This study addresses these challenges by enhancing the mechanical strength of electroless nickel plating through the crystallization of its amorphous structure via heat treatment, thereby improving its MRF processability. Initially, the MRF feasibility for the heat-treated electroless nickel plating layer was theoretically analyzed and subsequently verified through experimental analysis. Thereafter, the MRF process was applied to heat-treated electroless nickel plating specimens, and their surface conditions were evaluated for comparison with theoretically predicted values and determining the optimal heat treatment conditions. In particular, the electroless nickel plated surface heat-treated at 350&#xa0;°C exhibited an approximately 85% reduction in surface roughness compared to conventional electroless nickel plating, with an approximately two times higher material removal rate per unit time.</p>