Targeted delivery of therapeutic transgenes into specific cells remains a highly relevant challenge for tissue engineering and future gene-based therapies. We have designed streptavidin-pseudotyped lentiviral particles which upon coupling with biotinylated magnetic carbon-coated cobalt nanoparticles could be guided by magnetic fields to site-specifically transduce desired target cells in culture as well as in mice. Magnetic patterns projected onto monolayer cultures were replicated by fluorescent cells following targeted transduction by magnetic lentiviral particles engineered for constitutive expression of the green fluorescent protein (GFP). Even after intravenous injection into mice magnetic GFP-transgenic lentiviral particles could be guided to a preferred transduction site in the animal using a magnetic field. Magnet-guided transgene delivery producing desired patterns of transduced cell populations may enable the design of defined tissue topologies and provide site-specific transduction of therapeutic transgenes for cell-specific interventions in future gene and cancer therapies.