To address the issues of poor wear resistance and frequent failure in 65Mn steel used for agricultural machinery rotary tillage parts, an Fe/Ni-WC gradient composite coating was deposited on the surface of a 65Mn steel substrate via plasma cladding technology. The surface crack formation of the coating was evaluated, and the variations in elemental composition, phase structure, and crystal structure across the coating were analyzed. Additionally, the hardness distribution and tribological properties of the coating were investigated. The results indicated that the gradient composition of the Fe/Ni-WC coating reduced crack incidence by 98.53%. Interlayer diffusion of the primary elements led to the formation of γ-Fe, γ-(Fe, Ni), Fe–Cr, W2C, and other carbides and borides. The average hardness of the Fe/Ni-WC top functional layer reached 785.97 HV0.5, approximately 2.79 times higher than that of the substrate. Wear tests revealed that the gradient coating exhibited a lower friction coefficient, narrower wear width, shallower wear depth, and reduced material loss compared to the substrate. In conclusion, plasma cladding of the Fe/Ni-WC gradient composite coating improved coating integrity and significantly enhanced the hardness and wear resistance of the 65Mn steel substrate.