Abstract: Using plasma-enhanced chemical vapor deposition, diamond-like carbon (DLC) films were deposited on 2024 aluminum alloy substrates. The effects of pulse voltage on the film microstructure, surface morphology evolution, and overall service performance were systematically investigated. The results show that as the pulse voltage increased, the film thickness gradually increased, while the hydrogen content and C–H bond concentration decreased. Meanwhile, the fraction of sp²-hybridized carbon increased, and the surface roughness initially decreased and then increased. At 1800 V, the film exhibited the highest surface flatness and density. As the pulse voltage increased, the film–substrate adhesion decreased, whereas the internal (residual) stress rose markedly at higher voltages. The film hardness and elastic modulus exhibited a non-monotonic dependence on pulse voltage, increasing initially and then declining; both peaked at 1800 V, reaching 16.75 GPa and 139.4 GPa, respectively. At this voltage, the friction coefficient was minimized and the H/Ef ratio was maximized, indicating superior wear resistance. In a 3.5 wt% NaCl solution, the DLC films acted as effective physical barriers, significantly suppressing the electrochemical corrosion of the substrate. The film prepared at 1800 V exhibited the highest charge transfer resistance and extremely low porosity, demonstrating the best overall corrosion resistance. As a critical process parameter, pulse voltage regulates plasma density and ion bombardment energy, thereby controlling the evolution of mechanical properties and chemical stability. This, in turn, determines the mechanical performance and corrosion resistance of the DLC films. These findings provide a solid theoretical basis for the fabrication of high-performance DLC protective coatings on aluminum alloy substrates.