The characteristics of silicon nanowires (SiNWs) with surface roughness are reported and analyzed for solar cell (SC) applications. The SiNWs are fabricated using a metal-assisted chemical etching process. The effects of the etching time and reaction temperature on the surface roughness and the performance of the SiNWs are investigated. Further, the optical and electrical characteristics of the roughed NW SC are numerically studied and optimized using 3D finite difference time domain and finite element analysis, respectively. The numerically optimized SiNWs with surface roughness offer high optical ultimate efficiency (η) of 32.51% with an enhancement of 15.98% over the smoothed SiNW. This is due to the surface textures of the nanowires which produce multiple light scattering between the NWs’ walls. This will enhance the optical path length through the NW and enrich its light absorption. The doping level of the surface roughness of NWs with p-type/intrinsic/n-type (p-i-n) axial configurations is also simulated to compute the optoelectronic performance of the suggested design. The p-i-n axial doped design offers a power conversion efficiency of 14.92%, whereas the conventional NWs have a power conversion efficiency of 13.16%.