Recently, a lot of attention is being paid to combine silicon nanowires (SiNWs) and the conventional micro-pyramid silicon (µT-Si) structures leading to SiNWs/µT-Si binary structures for efficient light harvesting. We report large-area fabrication of vertical SiNWs array over three-dimensional micro-pyramid structured silicon substrate through silver (Ag)-assisted electroless wet chemical etching in aqueous HF and AgNO 3 solution. The influence of AgNO 3 concentration has been investigated over the formation of the SiNWs. Vertical SiNWs formation takes place for lower AgNO 3 concentrations. For higher concentrations, random formation of NWs and depletion of the micro-pyramids is observed. The present study reveals strong influence of local morphology of micro-pyramids over NWs formation. The formation mechanism of such binary structures has been discussed in co-relation with dimensional features of the micro-pyramids and surface free energy. Such hierarchically textured binary structured silicon surfaces exhibit excellent light trapping properties reducing reflectance to as low as <3 % in broad spectral range. Further, such surfaces also have enhanced Raman spectra (~15-fold enhancement) as compared to only micro-pyramid Si surfaces, thereby having potential applications for photovoltaic devices as well as surface enhanced Raman spectroscopic investigations.