Metal-phenolic coordination chemistry provides a simple and rapid way to fabricate ultrathin films. Here, we report a facile strategy for the preparation of low-fouling and pH-degradable metal-phenolic network (MPN) capsules using a synthetic polyphenol derivative, poly(ethylene glycol) (PEG)-polyphenol, as a building block. PEG-MPN capsules exhibit reduced nonspecific protein adsorption and cell association compared with tannic acid (TA)-MPN capsules. In addition, they show faster disassembly at a biologically relevant pH (5) than TA-MPN capsules (80% in 5 h vs 30% in 10 days). PEG-MPN capsules combine both the low fouling properties of PEG and the advantages of the MPN-driven assembly process (e.g., fast assembly and pH-degradability).