The development of novel materials for the detection and removal of Hg2+ is a very important issue due to the acute toxicity of Hg2+. Herein, a novel supramolecular polymer P5BD-DPHB has been constructed by the collaboration of a naphthalimide functionalized-pillar[5]arene host (P5BD) and a bis-bromohexane functionalized-pillar[5]arene guest (DPHB). P5BD-DPHB could form a stable supramolecular gel (P5BD-DPHB-G). Interestingly, P5BD-DPHB-G shows selective fluorescent "turn-on" detection for Hg2+via cation-π interactions with high selectivity and sensitivity. Furthermore, the Hg2+ coordinated supramolecular gel P5BD-DPHB-HgG can detect I- successively. The detection limits for Hg2+ and I- are 1.65 × 10-9 and 1.84 × 10-8 mol L-1, respectively. Even more significantly, the xerogel of P5BD-DPHB-G could remove Hg2+ from aqueous solution with excellent recyclability and ingestion capacity, and with a Hg2+ removal rate of 98%.