Clinical virotherapy has been successfully approved for use in cancer treatment by the U.S. Food and Drug Administration; however, a number of improvements are still sought to more broadly develop virotherapy. A particular challenge is to administer viral therapy systemically and overcome limitations in intratumoral injection, especially for complex tumors within sensitive organs. To achieve this, however, a technique is required that delivers the virus to the tumor before the body’s natural self-defense eradicates the virus prematurely. Here we show that recombinant adeno-associated virus serotype 2 (AAV2) chemically conjugated with iron oxide nanoparticles (∼5 nm) has a remarkable ability to be remotely guided under a magnetic field. Transduction is achieved with microscale precision. Furthermore, a gene for production of the photosensitive protein KillerRed was introduced into the AAV2 genome to enable photodynamic therapy (PDT), or light-triggered virotherapy. In vivo experiments revealed that magnetic guidance of “ironized” AAV2-KillerRed injected by tail vein in conjunction with PDT significantly decreases the tumor growth via apoptosis. This proof-of-principle demonstrates guided and highly localized microscale, light-triggered virotherapy.