The cascade Forster resonance energy transfer (FRET) is a multiple step nonradiative process that occurs between more than one pair of energy donor and acceptor molecules on the scale less than 10 nm, and it has played an important role in developing fluorescence sensors because of its simplicity and sensitivity. Here, blue-emitting neutral poly(vinyl carbazole), greenemitting tris-(8-hydroxy-quinoline)aluminum, tris[2-(4,6-difluorophenyl)pyridinato-C2,N]iridium (III), and orange-emitting 4-(dicyano-methylene)-2-methyl-6-(4-dimethylamino-styryl)-4H-pyran (DCM) are coassembled with layered double hydroxide nanosheets using a layer-by-layer method to form inorganic/organic composite luminescence ultrathin films (UTFs). The UV-vis absorption, scanning electron microscopy, and small-angle X-ray diffraction results demonstrate that the fabricated ultrathin films are ordered, linear growth, and homogeneous. The photoluminescence spectroscopy demonstrates that the 2D cascade FRET process is realized and a significant enhancement of light emission and extended lifetime of DCM dye is obtained in the UTF. Furthermore, these composite UTFs show fast, sensitive, and selective fluorescence signal patterns toward common volatile organic compounds (VOCs) based on interfering the 2D cascade FRET process, implying its potential application in the VOC selective sensing field.