Signal amplification is one of the simplest and most effective strategies for effi- ciently improving the performance of emerging sensing, imaging, and therapy technologies. For the amplification of detection signals and enhancement of therapeutic effects, the light-harvesting and energy-transfer properties of conjugated polymers (CPs) have made this class of materials a key platform for amplifying detection signatures that betray the presence of biomarkers and enhancing therapeutic action. In this review, we first summarize CP-ampli- fied fluorescence sensing in homogeneous solution and on solid supports. We then discuss how CPs can be integrated into amplified in vitro and in vivo imag- ing with the use of both fluorescence and self-luminesce phenomena. We further illustrate and examine the importance of CPs as amplifiers through examples of enhanced photodynamic therapy. To conclude, we discuss the challenges, opportunities, and perspectives for the future development of this field.