We apply mesoporous thin silica films with nanometer-sized pores as drug carriers and incorporate the widely used anticancer drug Doxorubicin. Through single-molecule based measurements, we gain mechanistic insights into the drug diffusion inside the mesoporous film, which governs the drug-delivery at the target-site. Drug dynamics inside the nanopores is controlled by pore size and surface modification. The release kinetics is determined and live-cell measurements prove the applicability of the system for drug-delivery. This study demonstrates that mesoporous silica nanomaterials can provide solutions for current challenges in nanomedicine.