This research examines the magnetoresistance (MR) behaviour of Co/Cu superlattices with a fixed Co layer thickness of 20 Å, emphasizing the effect of varying Cu layer thickness on MR across a wide temperature range of 4.2–300 K. The study specifically explores how different Cu layer thicknesses and interface compositions impact spin-dependent electron scattering, which in turn affects the MR ratio. The theoretical framework suggests that the MR is highly sensitive to changes in Cu layer thickness due to the modification of electron scattering mechanisms at the Co/Cu interfaces. Through numerical simulations, it is observed that the MR decreases significantly as the Cu layer thickness increases from 5 Å to 150 Å, particularly at lower temperatures. The agreement between theoretical predictions and experimental measurements underscores the importance of Cu layer thickness and interface and surface integrity in achieving optimal MR performance in electrodeposited Co/Cu multilayers.