Highly uniform and multifunctional hollow mesoporous silica nanocages that combined excellent properties (good biocompatibility, fluorescence imaging, drug delivery, and dual-mode cancer therapy) in one single system were synthesized. Dye molecules labeled in the nanocages could be used as traceable detectors in fluorescence imaging. A chemotherapeutic drug, doxorubicin (DOX), has been loaded into the nanocages with a high storage capacity due to the large cubic cavities and could be released through the penetrating mesoporous channels in a sustained fashion. Hematoporphyrin molecules were also covalently doped in the nanocages and allowed for photodynamic therapy. More importantly, a cooperative, synergistic therapy combining chemotherapy and photodynamic therapy exhibited high therapeutic efficacy for cancer therapy in vitro.