The current study depicts an exclusive technique to detect fluoride ions in water using a cost-effective self-powered sensing device using nanostructured Mn-doped BaTiO3 as the detecting element. The device is powered by a piezoelectric nanogenerator (PENG), whose substrate was modified by addition of the Mn-doped BaTiO3 nanomaterial and carbon nanotubes as fillers to generate high PENG output voltage sufficient for driving the fluoride detector. A highest voltage of 43.6 V and current of 1.23 μA was achieved by the modified PENG substrate. This substrate was then connected as the input to the fluoride detection film via a rectified voltage divider circuit. The device was found to detect fluorides in water mixed at different concentrations, with the highest sensor response of 32.69 and a limit of detection as low as 1.18 μM. This work enlightens a unique method to detect fluoride in a very efficient and inexpensive way.