Gold nanoparticles (AuNPs) have demonstrated increasingly wide applications in drug delivery due to their unique physicochemical and optical properties as well as low toxicity. Compared to the organic nanocarriers for therapeutic agents, AuNPs have shown superior performance as drug delivery vectors, including the inert nature, well-developed synthesis strategies, tunable size, and flexible and easy surface modification with various chemical and biological molecules. In this review, we emphasize on the applications of AuNPs in the aspect of improving pharmaceutical property and therapeutic efficacy of drugs, especially those covalently and noncovalently connected to the surface of AuNPs. Acting as a solid core to link drugs and their derivatives, AuNPs provide the nano-prodrug system with compressed size, high loading efficiency, three-dimension structure, and enhanced cellular uptake capability. With the intensive and systematical investigation of the drug-connected AuNPs, several important issues will become the hot but emergent topics for future research in this field, such as the toxicity in live human subjects, ultimate destination, and possible pathways and mechanisms for their absorption, circulation, distribution, metabolism, and excretion.