Development of rapid and effective analytical sensing strategy for fluoride ion in aqueousmedium is an utmost need in view of naturally widely spread fluoride contaminated groundwater or drinkingwater which causes numerous adverse effects on human health. In prospect of the need, we have developed asimple synthetic route for poly(ethylene glycol)-400 crowned silver nanoparticles for sensitive sensing offluoride ions in aqueous medium. The silver nanoparticles embedded with polyethylene glycol-400 (PEG-400) were synthesized as colloids by heating an aqueous solution of silver nitrate and PEG-400 with trisodiumcitrate. The effects of temperature, the concentration of silver nitrate and trisodium citrate werethoroughly investigated and optimized. The structure and morphology of prepared poly(ethylene glycol)-400crowned silver nanoparticles as colloids was thoroughly examined by UV–visible spectroscopy, Fouriertransform infrared (FTIR) and field emission scanning electron microscopy (FESEM). The prepared poly(-ethylene glycol)-400 crowned Ag Nps selectively detects fluoride ion in an aqueous medium at low concentration(0.098 mg/L) via the change in optical properties. The change in optical properties of Ag Nps wasinvestigated with UV-visible and morphological changes were examined with field emission scanningelectron microscope. The FESEM and UV-Visible analysis demonstrate that synthesized Ag nanoparticles areagglomerates with fluoride ions with immediate visual color change from yellow to colorless.