A simple process is developed to fabricate metallo-supramolecular nanogels (MSNs) by the metallo-supramolecular-coordinated interaction between histidine and iron-meso-tetraphenylporphin. MSNs are composed of histidine-modified dextran (DH) and iron-meso-tetraphenylporphin (Fe-Por) and exhibit excellent biocompatibility and stability. MSNs show pH responsiveness in the intracellular mildly acidic environment, which has great potential for acid-triggered drug release delivery. In vitro drug release profiles demonstrate that the pH-dependent disassembly of MSNs to histidine and Por results in a quicker release rate of loaded-DOX at pH 5.3, while at pH 7.4 MSNs could hinder the release of loaded-DOX due to the enhanced stability of MSNs.