Ordered mesoporous carbons were prepared by the self-assembly of Mimosa tannin, a natural polyphenolic molecule, and a micellar solution of Pluronic® F127, used as soft template. The synthesis was carried out at 20 °C using water as the only solvent and without crosslinker agent (i.e., formaldehyde). When tannin, at any pH lower than 4.2, and Pluronic solutions were mixed, a phase separation mechanism immediately occurred due to the strong interaction between both polymers.