Spurred by numerous achievements in nanoscience and nanotechnology, the evolution of nanoparticulate drug delivery systems (nano-DDSs) is in its rapid growth period and attracting considerable attention due to their unique advantages in biomedical applications. Natural particulates ranging from mammalian cells to bacteria possess their own distinctive delivery processes and mechanisms, which inspires more design and development of cell-based DDSs by integrating the innate functions of cells with the nanoscale characteristics of nanoparticles. In this review article, we focus on the recent advances in cell-based DDSs for site-specific delivery of therapeutics and enhanced treatment of diseases. The promise and perils of cell-based DDSs are also discussed.