A new kind of highly durable, electrically conductive UHMWPE fibers coated with copper was fabricated through a novel, simple, and universal process in this paper. Poly(acrylic acid) was anchored on the surface of UHMWPE fibers through radiation-induced graft polymerization. Then the grafted fiber adsorbed silver ions and was placed in a plated bath for electroless deposition of copper to yield conductive fibers. The result of single fiber tensile strength ascertained that the metallized fibers retained the excellent mechanical properties of original fibers. Importantly, the formation of three-dimensional network structures consisted of grafted polymer chains and metal particle deposited on the surface of UHMWPE fiber, which can effectively improve the adhesion between the copper and the fibers, providing excellent electrical stability and durability even after 30 accelerated washing cycles. Therefore, this method can be extended as a universal approach to fabricating high-performance conductive fibers or fabrics from other kinds of polymer substrates.