A novel strategy was developed for the fluorescence detection of nitrite (NO₂⁻) in real samples. The method is based on the reaction of water-dispersible graphite-like carbon nitride (w-g-C₃N₄) with nitrite (NO₂⁻) in an acidic medium to form a new kind of weak fluorescence species. Under optimal conditions, the limit of detection (LOD) for nitrite (NO₂⁻) detection was determined to be 0.16 nM (S/N = 3), and the relative fluorescence intensity versus logarithm concentration of nitrite (NO₂⁻) showed good linearity in the range from 0 to 58.5 μM with R² = 0.997. This probe displayed several appealing properties including low-cost, simplicity and convenience, high sensitivity, and excellent selectivity.