Silver nanoprisms with strong absorption in the near-IR have been synthesized using a modification of the photoinduced method by illuminating preformed silver seeds under different illumination conditions. Low-intensity light-emitting diodes and white light combined with different color filters are used as light sources. The lateral dimensions of the nanoprisms are found to be correlated in a quasilinear fashion with the emission wavelength and the position of the main in-plane dipole plasmon band. The structural characterization of the Ag nanoparticles, carried out using scanning electron microscopy., transmission electron microscopy (TEM), high-resolution TEM. and electron diffraction, reveal that the particles are flat and have a single-crystal face-centered-cubic structure. Time-resolved studies suggest that the nanoprisms are formed by steady consumption of the original Ag seeds with little variation of the aspect ratio after a short induction time.