It is extremely difficult if not impossible to effectively and precisely regulate the luminescence of organic chromophores from different electronic excited states through external stimuli for use in light-conversion devices. This is mainly due to the difficulty in breaking Kasha's rule by large energy separation and stabilization of different emissive electronic excited states. Here, the authors address this great challenge in a single experiment by expanding the utility of a monounsaturated omega-9 fatty acid (oleic acid) capped with organic chromophores as a new and efficient luminescent regulator. More specifically, the authors have successfully promoted the use of oleic acid as an efficient and reversible switch that can precisely regulate chromophore luminescence. These time-resolved absorption and luminescence experiments, along with density functional theory calculations have clearly demonstrated that ultrafast electron transfer from oleic acid to the difluoroboron β-diketonate (DFBK) chromophores efficiently blocks the intramolecular charge transfer process of DFBK chromophores, and activates the locally excited state luminescence, leading to different emission colors from different electronic excited states for ultralow UV-light detection and high-performance data encryption.