Gene therapy holds promise to suppress carcinomas but still remains far removed from clinic because of the lack of a safe and effective delivery system. Besides enhancing transfection efficiency, the difficulty in gene therapy is how to deliver sufficient gene molecules to the site of interest. Herein, the rational design of surfactant-free lipo-polymersomes (LPPs) to overcome these problems is reported, simultaneously using a lipid-stabilized double emulsion approach. The LPPs are designed to conceal the cationic lipids and plasmid DNA inside the core along with iron oxide nanoparticles/polymer interlayer and a relatively neutral lipid shell to avoid the undesired interaction during circulation, leading to high accumulation in the tumors of mice. Furthermore, guided by an external magnetic field and the folic acid (FA) that target tumors via folate receptor-mediated endocytosis on the cell surface, the vectors demonstrate a 30-40-fold increase in cell uptake. Moreover, this synergistic tumor-targeted approach can enhance a 10-fold increase in in vivo transfection efficacy by promoting the delivery of LPPs to cancer cells and facilitating the endosomal escape of gene molecules. The new insights and capabilities represent a major step in nanovector engineering for safe and efficient gene delivery.