In this study, the effects of poly(oxy-1,2-ethanediyl), alpha-(4-nonylphenyl)-omega-hydroxy-,branched (ANP) under various concentrations on the Cu-electrodeposition on the brass surface were investigated. The leveling, grain refining, and brightening agent effects have been identified for the used ANP additive. In addition, the Cu-electrodeposits morphology was studied by Scanning Electron Microscopy (SEM) coupled with Energy dispersive X-ray analysis (EDS) and Atomic Force Microscopy (AFM). The cyclic voltammetry technique, the quantum chemical calculations, and molecular dynamics (MD) simulations were also used to explain the Cu-electrodeposition mechanism. Finally, electrochemical measurements were employed to study the ANP effect on the Cu-electrodeposit resistance in a 3.5 wt% NaCl medium. The cyclic voltammetry demonstrated that the studied system is irreversible and that the kinetics of the Cu-electrodeposition reaction are controlled by diffusion. In addition, the SEM/EDS and AFM results revealed that the ANP addition increases the Cu-electrodeposit with an improvement in its roughness degree and crystallite size. In the same context, the quantum chemical calculations and molecular dynamics (MD) simulations suggested that ANP may be strongly adsorbed on the brass and Cu-electrodeposit surfaces. Toward the end, the electrochemical measurements results indicated that the polarization resistance of the Cu-deposit increases with the presence of ANP in the copper bath, demonstrating its good corrosion resistance in marine medium.