In the present study, we present a unique sensing platform relies on a silicon nanowire (SiNW) and reduced graphene oxide (rGO) hybrid nanostructure capped with (3-aminopropyl) triethoxysilane (APTES) and polyethylene glycol gold nanoparticle (PEG-AuNPs). Herein, MACE technique was applied to synthesize SiNWs, which was then used to develop a sandwich hybrid nanostructure by casting of rGO/APTES/PEG-AuNPs on its surface under room temperature and was characterised using various techniques. The developed PEG-AuNPs/rGO@APTES/SiNWs hybrid nanostructure-based sensing platform was used to detect two types of arsenic, that is, arsenite (As3+) and arsenate (As5+) using cyclic voltammetry in a sensitive and selective manner wherein the presence of arsenic species in real sample (blood) as well as standard samples was recorded.