Chiral recognition is vital in pharmaceutical and life sciences, as is often the case where for a drug one enantiomer cures while the mirror-image other kills. Many techniques, including nuclear magnetic resonance (NMR), circular dichroism (CD), gas chromatography (GC), mass spectrometry (MS), and high-performance liquid chromatography (HPLC), have been developed to differentiate these isomers. Among these methods, photoluminescence-based enantiomeric discrimination is of interests in the past several decades as it is real-time, low-cost, and highly sensitive. Many luminescence chiral selectors based on 1,1-bi-2-naphthol, tetraphenylethene, and polymers have been reported, with sensing modalities ranging from emission intensity to lifetime, and to color. Room-temperature phosphorescence (RTP), on the other hand, exhibits extra benefits, such as red-shifted wavelengths into the visible region and longer lifetimes for enantiomeric discrimination with higher sensitivity. RTP chiral selectors are usually rigid media such as inclusion complexes (e.g., cyclodextrin ) or solid-state substrates (e.g., menthol) which are resistant to diffusing molecular oxygen and other quenchers, and the signal distinction, albeit scarce in examples, is subtle with only minor differences showing up in lifetimes between the two enantiomeric phosphors. The subtlety is not surprising since such a discrimination relies solely on the limited environmental disparity effects, which mainly dictate the difference in interactions between chemical groups of the analyte and substrate. Consequently, the key to success in RTP chiral recognition is to amplify such a disparity. Herein, we report a new RTP chiral recognition method by using an organic guesthost system consisting of a brominated phthalimide host and an amino naphthalimide guest (Scheme 1), where the RTP intensity can be expressed by the following relationship: IRTP  ET  kISC  1/knr, where ET is the efficiency of excited-state energy transfer, kISC is the rate of intersystem crossing, and knr is the nonradiative decay rate. As Scheme 1 indicates, we expect that all three variables are related to chirality (e.g., spin polarization and orbital overlap during energy transfer) or chirality-related secondary effects (e.g., knr and kISC difference from presence or absence in close molecular contacts with external heavy-atom effects), so that amplification of the RTP intensity difference could be significant enough for the naked eye.