Water-soluble conjugated polymers have attracted much attention in the biosensor community because of recent exciting experimental results. The transfer of excitation energy along the whole backbone of the conjugated polymer to the reporter results in an amplified fluorescence signal, which makes them useful as optical platforms in highly sensitive chemical and biological sensors. In this Research News Article, we provide a brief review of recent developments it? this field, focusing especially on the application of water-soluble optical conjugated polymers in biomacromolecule (DNA and protein) detection.