Microsphere technology serves as an efficient and effective platform for cell applications (in vitro cell culture and in vivo cell delivery) due to its mimicry of the 3D native environment, high surface area:volume ratio, and ability to isolate the entrapped cells from the environment. Properties of cell-laden microspheres are determined by the type of application and the cell. While high cell densities are preferable for large-scale therapeutic biomolecule production in vitro, an immunoprotective barrier is most important for allogeneic pancreatic islet transplantation into patients. Furthermore, the biological cells require a suitable microenvironment in terms of its physical and biochemical properties. Here, we discuss applications of cell-laden microspheres and their corresponding design parameters.