Large-scale and uniform copper(I) sulfide (Cu2S) nanowires have been successfully synthesized via a cheap, fast, easily handled, and environmentally friendly approach. In addition to the reductive properties of the biomolecule-assisted method, they also have a strong shape-or size-directing functionality in the reaction process. The field-emission properties of the Cu2S nanowires in a vacuum were studied by the Folwer–Nordheim (F–N) theory. The Cu2S nanowires have a low turn-on field at 1.19 V/μm and a high enhancement factor (β) of 19,381. The photocatalytic degradation of Cu2S nanowires was investigated by the change in the concentrations of rhodamine B (RhB) under UV illumination. These outstanding results of Cu2S nanowires indicate that they will be developed as good candidates as electron field emitters and chemical photocatalysts in future nanoelectronic devices.