Novel cancer-targeting nanotherapeutics are developed based on mesoporous silica nanoparticles (MSN) loaded with metal complexes, for potent activity against cancer. MSN was synthesized by a surfactant-templated method. The nanomaterials are designed, through post-synthetic surface-functionalization with the capability to release Ruthenium- and Iridium-based drugs from MSN nanomaterials by lowering pH value. This effect would lead to preferential cancer-targeting due to the more acidic tumor tissue in comparison to the healthy tissue. Novel Ru(II) and Ir(III) coordination compounds were also synthesized, containing the same ligands which are contained on the surface of MSN, and their anticancer activity was evaluated with and without their covalent attachment to MSN. The constructed series of novel nanomaterials and coordination compounds were characterized by scanning electron microscopy, thermogravimetric analysis, infrared spectroscopy, X-ray crystallography, and elemental analysis. The characteristics of prepared metal complexes and novel nanomaterials demonstrate high potential for their effective application in targeted cancer treatment.