The melanoidin from soluble coffee is utilized as a material-independent, multipurpose coating material. Instantaneous complexation of the coffee melanoidin (CM) with ferric ion (Fe3+) leads to surface-adhesive aggregates, inducing sequential film deposition. Various chemical groups of the CM also allow for post-functionalizations of the CM film, including surface-initiated, ring-opening polymerization and bioinspired silicification. In addition, the CM-based coating is applied to single-cell nanoencapsulation with a strategy of biphasic interfacial reactions. The method is highly cytocompatible (viability >98%), and the CM shell is cytoprotective against lytic enzymes. The coated cells inherit the characterictics of the CM, such as post-functionalizability and antioxidant property. Considering that surface-coating technologies with cytocompatible natural polymers have widely been used for engineering bioentities, the CM-based coating strategy would provide an advanced option for biomedical applications.