Upconversion nanoparticles (UCNPs) have outstanding optical and magnetic properties, which make them extremely suited for application in cancer phototherapy and imaging. They efficiently convert low energy near infrared (NIR) light to higher energies in the visible. The so-generated upconverted luminescence can be exploited to photoactive anticancer metal complexes, a promising class of compounds studied as novel photochemotherapy agents. UCNP-mediated NIR activation will allow overcoming metal complexes’ light absorption limitations, simultaneously achieving considerably higher tissue penetration and preserving photochemical reactivity. Indeed, the rich photochemistry of metal complexes can result in unique cell killing modes, critically important in the development of novel anticancer prodrugs.The project aims at investigating the use of UCNPs in the photoactivation of promising anticancer metal complexes, and more specifically at developing new nanomaterials where these two components are integrated to give a superior prodrug. Anchoring photoactive anticancer coordination compounds on UCNPs can produce materials with optimal photophysical and photochemical properties for chemotherapy. Moreover, the chemical versatility of UCNPs offers opportunity for functionalization with biological vectors, which improve biocompatibility, targeting and selectivity features of these integrated nanomaterials in cells and tissues. Remarkably, UCNPs are also excellent new candidates for multimodal (optical/MRI/PET) bioimaging. Their upconverted luminescence, magnetic resonance relaxivity and radioactivity (ease of 18F-labeling) will serve to visualize fundamental biological events with high spatial resolution, which are key to study the photoactive nanomaterials’ anticancer action as well as for their medical use. All such features combined together have the potential to deliver innovative therapeutic and imaging agents for cancer phototherapy.