The possibility of improving the compatibility of and the adhesion between liquid-crystalline poly(oxybenzoate-co-oxynaphthoate) (Vectra) and polycarbonate (PC) by adding a stable compatibilizer based upon the transesterification between liquid-crystalline poly(oxybenzoate-co-ethylene terephthalate) (POB/PET) (60/40) and polycarbonate was investigated. The goal was to provide a physical interaction between the matrix polymer and the liquid-crystalline polymer through a third polymer that contained similar chemical structural units to those in both polymers. It was found that at proper compositions the adhesion between Vectra and PC was greatly improved by the presence of the compatibilizer, as indicated by the morphological evidence. These ternary liquid-crystalline polymer blends displayed improved ultimate tensile stress (30% increase as compared to PC) and elongation at break (seven times as compared to binary blend) even under a nominal injection-moulding process. The impact property of the ternary liquid-crystalline polymer blend was also improved as compared to that of the binary liquid-crystalline polymer blends.