Polyinosinic-polycytidylic acid (poly(I:C)) is a synthetic double-stranded RNA (dsRNA) analog able to induce apoptosis in different cancer cells by the activation of toll-like receptor 3 (TLR3) and cytosolic helicases, retinoic acid inducible gene I (RIG-I) like receptors. In this work, we have synthesized and thoroughly characterized a core-shell liposome-silica hybrid (LSH) nanoparticle (NP) made of a silica core surrounded by a multicomponent cationic lipid bilayer. In view of in vivo applications, a variant with polyethyleneglycol (PEG) grafted onto the lipid surface was also synthesized. Poly(I:C)-loaded LSH NPs were characterized and optimized in terms of their chemical-physical properties by using dynamic light scattering (DLS), micro-electrophoresis and transmission electron microscopy (TEM). The ability of this new technology to kill cancer cells was validated in PC3 prostate cancer and MCF7 breast cancer cells by MTT proliferation assay, flow cytometry and fluorescence confocal microscopy. We found that negatively charged poly(I:C)-loaded LSH NPs are more efficient than their liposome counterpart in eliminating cancer cells, thus representing excellent candidates for both in vitro and in vivo drug delivery applications.