A polyvinylpyrrolidone (PVP)-based fluorescent film with stable optical properties is successfully prepared in one pot without any additive. The reaction mechanism of ring-opening and self-crosslinking of linear PVP is proposed and demonstrated. The morphologies and the nanostructures of the fluorescent film as well as the unmodified film are investigated. The dye is incorporated into the film networks via covalent linkages, thus leading to the highly stable optical properties. The facile and effective synthesis approach opens a new way for the design of other multi-functional composite materials based on linear PVP.