The present invention relates to a functional copper sulfide composition and a functional fiber prepared from same, and more particularly, to a functional copper sulfide composition comprising a copper salt, a metal salt, a reducing agent, a sulfur compound, a catalyst, a polyvalent amine, an alkaline compound, and a pH adjusting agent, and a functional fiber prepared by treating a fiber with the composition. The present invention may provide a functional fiber which maintains the color thereof and has excellent conductivity, laundering resistance, washing resistance, durability, moisture resistance, alkali resistance, etc., even after repeated washings or long-term usage. Moreover, the functional fiber according to the present invention is excellent in terms of antibacterial and deodorizing properties, emission of far infrared radiation, scar treatment, skin aging prevention, heat storage and heat insulation, radiation shielding, and static removal, and may thus be widely used in clothing applications such as clothes, socks, gloves, bands, abdominal supports, masks, hats, bandages, scarves, hospital gowns, etc., industrial applications such as bedding, burn pads, industrial filters, fillers, etc., and military applications.