In the past decade, people have conducted extensive research on the synthesis and application properties of various functionalized pillararenes. Pillararenes show good application prospects in the field of sensors due to the rich host‒guest recognition in their rigid electron-rich cavities. However, most reported pillararenes are functionalized by alkoxy modification, which results in poor charge transfer nature and weak fluorescence response. A π-conjugated charge-transfer system P5BN was obtained by introducing electron-donating triarylamine (Ar3N) and elec-tron-deficient triarylborane (Ar3B) into pillar[5]arene skeleton, which significantly improved its luminescence behavior and was further used for fluorescence detection applications. The molecular structure showed that P5BN provided a good macrocyclic cavity to encapsulate amino acids molecules of suitable size. We found that P5BN, as a fluorescent sensor, showed a highly sensitive and selective response to L-arginine (L-Arg), resulting in a significant enhancement of the fluorescence at 408 nm of P5BN, with the lowest detection concentration being 2.21 × 10‒8 mol/L. The recog-nition mechanism was demonstrated through experiments and DFT theoretical calculations.