A mononuclear zinc complex is shown to act as a highly selective naked-eye-based chemosensor for pyrophosphate (PPi) in aqueous solution. Based on the keto–enol transformation process, addition of PPi made the color of the sensor complex change from red to colorless. Moreover, electrospun nanofibers from the mononuclear zinc complex could detect PPi on site and in real-time and the color of the nanofibers changes rapidly after they were immersed in an aqueous solution of pyrophosphate.