Light harvesting luminescent multichromophores that are configured upon excitation to transfer energy to, and amplify the emission from, an acceptor signaling chromophore in energy-receiving proximity therewith are provided. Also provided are compositions for labelling a target. The labelling composition may include a donor light harvesting multichromophore and an acceptor signaling chromophore in energy-receiving proximity to the donor light harvesting multichromophore. Also provided is an aqueous composition for labelling a target, including: a donor light harvesting multichromophore; an acceptor signaling chromophore in energy-receiving proximity therewith; and a sensor biomolecule. Methods for using the subject compositions are also provided.