The synthesis of large lattice mismatch metal-semiconductor core–shell hetero-nanostructures remains challenging, and thus the corresponding optical properties are seldom discussed. Here, we report the gold-nanorod-seeded growth of Au–CdS core–shell hetero-nanorods by employing Ag2S as an interim layer that favors CdS shell formation through a cation-exchange process, and the subsequent CdS growth, which can form complete core–shell structures with controllable shell thickness. Exciton–plasmon interactions observed in the Au–CdS nanorods induce shell thickness-tailored and red-shifted longitudinal surface plasmon resonance and quenched CdS luminescence under ultraviolet light excitation. Furthermore, the Au–CdS nanorods demonstrate an enhanced and plasmon-governed two-photon luminescence under near-infrared pulsed laser excitation. The approach has potential for the preparation of other metal-semiconductor hetero-nanomaterials with complete core–shell structures, and these Au–CdS nanorods may open up intriguing new possibilities at the interface of optics and electronics.