This review highlights recent advances in the preparation of silica nanoparticles (SNPs) functionalized with porphyrins and phthalocyanines for application in cancer photodiagnostic and photodynamic therapy (PDT). The use of photosensitizer-SNP formulations has emerged recently as a new nanomedicine for cancer research owing to their unique physicochemical properties, which make them useful for photo-biomedical applications. In order to study their photobiological properties, diverse chemical strategies involving covalent and non-covalent bonding have been used to load photosensitizers in/on SNPs.