A well-known fluorophore molecule pyrene was encapsulated into a stable metal organic framework by in situ encapsulation method. The existing metal-organic framework (MOF) called UiO-66 (UiO = University of Oslo) was served as host material for pyrene fluorophore. The fluorescence of pyrene was quenched after encapsulation inside the porous host. Recovery of quenched fluorescence was accomplished by anion induced host dissolution followed by release of fluorophore molecule. Using this anion induced dissolution; a selective sensing of fluoride anion in pure aqueous was achieved. It showed a fast response time, excellent selectivity and sensitivity for sensing of fluoride anion via fluorescence ‘turn-on’ mechanism. The excellent detection performance of this method in aqueous medium makes it a promising method for real-field water monitoring utilizing MOF material.