Poly[4-(1′-pyrenyl)styrene was synthesized for the first time, its photophysical properties were explored, and among them, the fluorescence with a high absolute quantum yield was discovered. Data acquired using the fluorescent titration revealed the opportunity to detect model nitroaromatic explosives at detection limits varying in the range from 10−6 to 10−7 mol L−1. The results reported herein for the homopolymer were compared with the corresponding data for poly[styrene-co-4-(1′-pyrenyl)styrene] copolymer synthesized previously.