A highly sensitive aromatic nucleophilic substitution reaction between BODIPY dye (1) and ammonia is explored and demonstrated as a potential tool for ammonia vapor detection. The high specificity under room temperature conditions signifies real-time application of the designed approach for ammonia vapour monitoring under ambient environments. The recognition events revealed instantaneous chromogenic and fluorogenic display. The photophysical modulation could effectively be achieved in the solid phase of the dye, obtained through physical impregnation on a silica surface. The resulting approach is efficient for monitoring ammonia gas in the ppm to ppb range via both absorption and emission responses. This ammonia vapour chemodosimetry was unambiguously characterized through single crystal XRD and 2D-NMR (1H-19F NOESY).