Semiconducting nanowires (NWs) present new opportunities for developing electrical biosensors due to their inherent properties, including large surface‐to‐volume ratio, rapid signal response, configurability in electronic devices, and nanoscale footprint comparable to biomolecular and subcellular structures. Field‐effect transistors (FETs) based on silicon nanowires (SiNWs) have proven to be a powerful and versatile tool in the biomedical fields. Recent advances in SiNW‐FET biosensors, including fundamental aspects and working principles, preparation of nanowires, and surface functionalization, as well as applications in biological analysis and cellular investigation, are discussed here. It is envisioned that nano‐FET devices will have several applications in fields such as clinical diagnosis, point‐of‐care testing, and screening for early disease.