Zinc-metal alloys with ferrous group metals such as Ni, Co, and Fe have been used for industrial applications due to their better corrosion performance compared to pure Zn. Among them, ternary Zn-Ni-Co alloys, which have superior corrosion resistance and magnetic features, have attracted extensive attention, and have been used as functional films in electro-mechanical system (EMS) devices and magnetic recording media. However, large differences in the reduction peak potential between Zn²⁺, Ni²⁺, and Co²⁺ restrict their codeposition because Zn-competitive adsorption hinders the discharge transfer of Ni²⁺ or Co²⁺. In view of the aforementioned statements, the effects of molar concentration ratios of Ni²⁺ : Co²⁺ : Zn²⁺ and the ascorbic acid (H₂Asc) concentrations in the bath on the surface features and textures of the Zn-Ni-Co alloys were assessed and characterized using FE-SEM, XRD, etc. Results showed that under the optimized condition of Ni²⁺ : Co²⁺ : Zn²⁺ = 4 : 5 : 1, the Ni content in the Ni-Co-Zn deposits reached 12.2%, which was instrumental in grain refinement. From the cyclic voltammetry curves, the potential of the reduction peak positively shifted from -1.47 V to -1.28 V, validating better codeposition with an appropriate H₂Asc concentration. SEM observations depicted a cauliflower-like texture with a crystal size of ~300 nm at a minimum growing stress of 9.04 MPa for the samples with 5 g/L H₂Asc concentration. From EDS analysis, with increasing H₂Asc concentration from 1 g/L to 5 g/L, the Ni + Co content in the Ni-Co-Zn deposits gradually increased but their Zn content decreased, which was attributed to the addition of H₂Asc in the form of [ZnHAsc]⁺ to offer more active sites for Ni or Co growth. Intermetallic compounds such as γ-Ni₅Zn₂₁, CoZn₁₃, and Ni₃Zn₂₂ were determined using XRD. The anticorrosive behavior was evaluated via potentiodynamic polarization (Tafel) tests in a 3.5%NaCl solution. The free corrosion potential (E_corr) positively shifted by ~200 mV for the samples with 5 g/L H₂Asc concentration and their corrosion current density (i_corr) has declined about 75% than those of the samples without H₂Asc. EIS results revealed a capacitive arc followed by a diffusion arc for the samples without H₂Asc, indicating pitting corrosion, and an inductive arc attached to a larger-radius capacitive arc for the samples with different H₂Asc concentrations, showing better corrosion resistance. This was due to the coexistence of the γ-Ni₅Zn₂₁ intermetallic phase and insoluble products [Zn(OH)₄]^2- that fully covered the Zn-dissolved active area to complete the corrosive channels via Cl^- diffusion, thus increasing the corrosion resistance of the Ni-Co-Zn alloys.