Individual mammalian cells were coated with cytoprotective and degradable films by cytocompatible processes maintaining the cell viability. Three types of mammalian cells (HeLa, NIH 3T3, and Jurkat cells) were coated with a metal–organic complex of tannic acid (TA) and ferric ion, and the TA–Fe^III nanocoat effectively protected the coated mammalian cells against UV-C irradiation and a toxic compound. More importantly, the cell proliferation was controlled by programmed formation and degradation of the TA–Fe^III nanocoat, mimicking the sporulation and germination processes found in nature.