Albumin has been used as a popular material for carrying imaging probes and/or drugs to provide efficient biomedical imaging and therapy. It is considered as an ideal material for in vivo applications, because albumin is naturally abundant in serum to show non-toxicity and non-immunogenicity. In addition, based on the convenience of chemical modifications, it is widely used for the delivery of diverse molecules including chemicals, proteins/peptides, and oligonucleotides. Albumin nanoparticles carrying these molecules have shown improved pharmacokinetic properties by providing longer circulation time and more disease-specific accumulation, and they are emerging as a promising carrier system for in vivo imaging and therapy. Constant efforts to improve the properties of albumin nanoparticles have led to a great progress in medical application, and recent examples of market approval and success are brightening the prospect of albumin-based nanocarrier formulations in the future. This article will summarize the developments in albumin nanocarriers for biomedical imaging and targeted drug delivery. This review will give an account of the different applications of albumin carriers with examples of some recent innovative works.