<p>The auto-fluorescence of cellulose filter paper has long been a bottleneck for its utilization as a solid-phase fluorescent substrate. This study thoroughly discussed the impacts of excitation wavelength, chemical modification, and the effects of heavy metal ions on these fluorescence properties of cellulose filter paper, and uncovered the quenching mechanism of Cd²⁺ ions on its auto-fluorescence. Specifically, the Cd²⁺ ions replaced the cations in sodium lignosulfonate, which effectively inhibited the auto-fluorescence of the filter paper. The high affinity of the sulfonic acid groups of the guaiacylpropane and butylpropane units comprising the sodium lignosulfonate for Cd²⁺ ions was further confirmed by calculating the highest occupied molecular orbital—the lowest unoccupied molecular orbital (HOMO–LUMO) gap (Δ<i>E</i>). Significantly, we developed a ratiometric fluorescent paper chip, Paper@Mn:ZnS, based on the auto-fluorescence of cellulose filter paper for Cd^2⁺ detection. This chip not only achieved a detection limit as low as 2.09&#xa0;nM but also was successfully applied to the detection of Cd²⁺ ions in actual polluted water samples.</p>