A hybrid drug delivery system was successfully fabricated by attaching a camptothecin (CPT)-based polymeric prodrug onto the surface of silver nanoparticles (AgNPs). PEG was employed as a macro-RAFT agent in RAFT polymerization to synthesize a branched star copolymer, to which CPT is linked through the photo-responsive o-nitrobenzyl linkage. In vitro tests indicate that the fluorescence of CPT in the polymeric prodrug is quenched by AgNPs based on the nanomaterial surface energy transfer (NSET) effect and the fluorescence recovers when the CPT molecules are released from hybrid nanoparticles. Thus, the variation of fluorescence intensity is bound up with the drug release behaviours, which may enable this AgNP-based drug delivery system to trace the intracellular drug release process and observe the distribution of released CPT in cells.