The present study investigates the effect of shot peening (SP) on the mechanical properties and surface roughness of 7075 aluminum alloy during different stages and conditions of heat treatment. The mechanical properties were determined by measuring Vickers microhardness profiles and residual stress profiles, while the amount of alloying elements present in the solid solution of the samples under different heat treatment conditions was determined by measuring the electrical conductivity. The results show that the increase in microhardness near the SP surface and the maximum compressive residual stresses are mainly related to the content of alloying elements in the solid solution. Surface roughness increases with increasing SP Almen intensity, and samples with the highest microhardness and residual stresses have the lowest surface roughness.