Grain size characteristics, mechanical properties, and corrosion resistance of Cu-10%Ni alloy heat treated at three different temperatures and times were investigated and compared with the synthesized alloy. Mechanical properties such as UTS, ductility, hardness, and impact strength were determined. An optical metallurgical microscope was used to examine the structural properties. ImageJ software was also used to measure the grain size distribution of the alloys. The corrosion behaviour of the produced Cu-10%Ni alloys is analyzed by potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS). After corrosion testing, the surface morphology of the exposed samples is analyzed by scanning electron microscope (SEM) equipped with energy dispersive spectroscopy. The corrosion rate of precipitate strengthened Cu-10%Ni alloy decreases and ultimate tensile strength, ductility, and hardness increase as the average grain size distribution decreases. The non-heat treated Cu-10%Ni alloy showed a peak value of corrosion rate and average grain size, but a lower value of mechanical properties. An increase in residual stress follows an increase in grain size distribution, which lowers the strength and increases corrosion rates due to more active sites. The research outcome has enabled the improvement of the mechanical and corrosion properties of Cu-10%Ni alloys as a component for marine and automobile applications.