One-dimensional tapered metallic nanostructures are highly interesting for nanophotonic applications because of their plasmonic waveguiding and field-focusing properties. Here, we developed an in situ etching technique for unique tapered crystallized silver nanowire fabrication. Under the focused laser spot, plasmon-induced charge separation of chemically synthesized nanowires is excited, which triggers the uniaxial etching of silver nanowires along the radial direction with decreasing rate, forming tapered structures several micrometers long and with diameter attenuating from hundreds to tens of nanometers. These tapered metallic nanowires have smooth surfaces showing excellent performance for plasmonic waveguiding, and can be good candidates for nanocircuits and remote-excitation sources.