Advanced technology in pharmaceutical science has encouraged the development of various applications of biomaterials in drug delivery. Zein, a plant protein, has attracted the interest of a number of researchers for applications in pharmaceutical technology, including solid dispersions, tablets, nanoparticles, microparticles, film coatings, powders, and gels. Diverse strategies for the use of zein for controlled drug release have been investigated and reported in the literature, especially engineering strategies for using zein conjugates to enhance oral bioavailability and targeted delivery, which has attracted interest in recent research. Although still limited, the ability to fabricate self-assembling nanoparticles loaded with molecules of interest offering functional groups for potential conjugation could yield zein-based conjugates with promise as materials for drug delivery. In the current review, recent studies of zein-based conjugates with outstanding features are discussed based on the various types of conjugation. The key physicochemical characterization methods for the chemical conjugation and identification of zein will be summarized. Further opportunities to develop zein-based materials through conjugation will provide promising alternative formulations for a number of drug candidates.