This paper examined the effect of surface preparation on the corrosion behaviour of copper coatings produced by electrodeposition and cold spray (CS) techniques. These methods are intended to be used to apply a copper coating on the used fuel containers as one of the multi-barrier layers to safely manage spent nuclear fuel long term in a deep geological repository (DGR). The as-received Cu samples exhibit significant variations in their surface chemistry and topography when compared to the polished samples. Furthermore, the microstructure and morphology of the CS coatings may not be homogeneous throughout their thickness. This study also examined the effect of polishing to different depths within the CS coatings on their resulting corrosion behaviour. To investigate the effect of surface preparation on the coatings’ corrosion properties, electrochemical measurements and complementary surface analysis techniques, such as Raman spectroscopy, X-ray micro-computed tomography (μ-CT), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), were employed. Consequently, it was observed that polishing the samples resulted in a more negative corrosion potential and an increase in corrosion current density, caused by the removal of the outer surface oxide layer formed during coating fabrication. However, there was no significant difference in the corrosion behaviour of Cu coatings and wrought Cu. Furthermore, despite the uneven distribution of voids and oxides throughout the CS coating, the corrosion properties were consistent. Therefore, it was concluded that polishing significantly changed the corrosion properties of as-received coatings, while the corrosion behaviour of the CS coating was almost homogenous through its depth.