This research explores the mechanical durability and surface integrity of the gradient-structured Mg5Zn0.2Ca alloy processed using surface mechanical attrition (SMA) treatment. Subsequently, the alloy’s micro-tensile, tribological, and scratch properties are examined. Between the SMA treatment conditions, ~5 and ~10   m/s shot velocities, the latter produces finer grains, a deeper gradient layer (2400 ± 200 μm), and appreciably higher surface hardness (112 ± 7%), YS (~2.4 times rise), and UTS (~1.4 times rise). Dry-sliding tribological evaluations under 5-20   N loads demonstrate an improvement in tribological performance with increasing SMA intensity, exhibiting substantially reduced wear volume (37-45% drop), specific wear rate, and coefficient of friction (0.2 ± 0.01). Subsequent scratch study under constant (50   N) and progressive (20-80   N) loading confirms the SMA-treated alloy’s resistance to localised deformation and improved surface stability under increasing contact stress.