Human serum albumin (HSA), a major transport protein component in blood plasma, has been reported recently to play many important roles in pharmacotherapeutics development. Owing to its promising intrinsic binding capability of drug molecules, HSA offers favorable characteristics and can be directly used as its monomeric formula or can be fabricated into protein based nanoparticle platforms to realize the effective delivery of therapeutic molecules into targeted diseases areas. In addition, HSA can also serve as a protein stabilizer or environment-responsive moieties to hybridize with the functional materials including polymers or inorganic nanoparticles through the covalent reactions or electrostatic interactions, and can thus greatly alter the relevant biological distribution and pharmacokinetic behavior to improve their therapeutic efficacy. By right, extensive studies have been conducted to develop HSA-conjugated pharmacotherapeutic agents toward effective in vitro and in vivo diseases diagnosis and treatment. The current review gives an in-detail account of the latest progresses of HSA-based carriers as functional protein materials, mainly with respect to its conjugation types, formulation aspects, and importantly their promising applications towards enhanced drug delivery and medical diagnosis.