Recently, laser-arc hybrid additive manufacturing (LAHAM) has emerged as a promising strategy for fabricating components with favorable performance. In this paper, we compared the microstructure and mechanical properties of Al–Zn–Mg–Cu alloy manufactured by wire + arc additive manufacturing (WAAM) and LAHAM and obtained strengthening by means of heat treatment. The microstructure consisted of coarse columnar grains with an average grain size of 70.4 µm in the WAAM-processed Al–Zn–Mg–Cu alloy. Compared to the WAAM specimen, the grain size of LAHAM specimen was reduced by 68%, and the eutectics distribution was more uniform. The high-densities η′ precipitates with the length of 10–30 nm appeared in the processed by LAHAM. The key achievement indicated that the ultimate tensile strength (590 ± 9 MPa) and elongation (8.6 ± 0.2%) for LAHAM-processed Al–Zn–Mg–Cu alloy after heat treatment were enhanced by approximately 87% and 169% than those in the deposited specimen.