Judicious combination of noble metals and smart gels makes cell imaging and drug delivery into one, which provides support for the integrated technology of diagnosis and treatment. In this work, the Ag nanoparticles (Ag NPs)/poly-(N-isopropylacrylamide-co-dimethylaminoethylmethacrylate) core-shell multifunctional composite nanosphere (Ag-p (NIPAM-co-DMAEMA)) was successfully synthesized by two-step one-pot method. The composite nanospheres had a particle size of approximately 200 nm and possessed multiple sensitive release properties, biocompatibility, and pharmacological activity. Importantly, it was found that cancer cells (CT-26) uptake more hybrid gels and exhibited stronger fluorescence, compared to normal cells (COS-7). This indicated that the hybrid gel had certain specificity and could be used for the imaging of cancer cells. Multifunctional composite nanospheres with optical and therapeutic functionality constructed by a simple method offered broad opportunities for cancer treatment and cell imaging.