Cell therapy offers the potential for curative treatment of cancers. Although T cells have been the predominantly used cell type, natural killer (NK) cells have attracted great attention owing to their ability to kill cancer cells and because they are naturally suitable for allogeneic applications. Upon stimulation by cytokines or activation by a target cell, NK cells proliferate and expand their population. These cytotoxic NK cells can be cryopreserved and used as an off-the-shelf medicine. The production process for NK cells thus differs from that of autologous cell therapies. We briefly outline key biological features of NK cells, review the manufacturing technologies for protein biologics, and discuss their adaptation for developing robust NK cell biomanufacturing processes.