Cytotherapies, or cell-based therapies, have spurred increasing interest due to the numerous potential therapies cells may be able to take part in. Magnetic nanoparticles have been found to be a very useful tool in developing cytotherapies. Primarily, magnetic nanoparticles have been used to track the distribution and activity of cells in vivo because they show large T2 and T2* shifts in magnetic resonance imaging. Magnetic nanoparticles paired with MRI have been able to track a wide variety of cells to multiple different tissues and diseases, helping to define the potential of cytotherapy and develop potential therapies. Beyond merely tracking, though, magnetic nanoparticles can confer new treatment abilities on cells when paired with magnetic hyperthermia. Cells can carry magnetic nanoparticles selectively to the site of therapy where they can absorb energy from oscillating magnetic fields, transferring that energy as heat to the surrounding tissue. Continuing to develop the partnership between cytotherapy and magnetic nanoparticles is likely to continue yielding exciting results.