Accurate fabrication of fluorescence probes to efficiently monitor and detect H2S levels in the fields of foodstuffs and physiology is crucial. Herein, we report two isomeric phenanthro[9,10-d]imidazole benzene sulfonamide-derived fluorescence probes (PI-2-SA and PI-4-SA), both of which display remarkable responses toward H2S over other analytes. The spectral characteristics of the two probes were investigated and are discussed in detail. By comparison, PI-2-SA was specific, sensitive (the limit of detection was ca. 12.3 nM), rapid (within ≤3 min) and dynamic (the rate constant was 0.02 s-1). Significantly, PI-2-SA was proved to be effective in monitoring the shelf-time progress of egg samples in real time as well as in the imaging of exogenous and endogenous H2S in HeLa cells.