Nature and its highly sophisticated biomaterials are an endless source of inspiration for engineers and scientists across a wide range of disciplines. During the last decade, concepts of bioinspired synthesis of hierarchically structured nano‐ and micromaterials have been attracting increasing attention. In this article, we have utilized the natural ability of fungi to absorb metal ions for a bioinspired synthesis of carbonaceous material doped by selected transition metals. As an all‐around metal accumulator, Hebeloma mesophaeum was selected, and it was cultivated in the presence of three transition‐metal ions: NiII, FeII, and MnII. The metal‐doped carbonized biomaterial possessed enhanced catalytic activity toward hydrazine oxidation, oxygen reduction, and cumene hydroperoxide reduction. Thus, we have shown possible transformation of a waste product (fungi grown on a contaminated soil) into a value‐added carbonaceous material with tailored catalytic properties. This bioinspired synthesis can outline an attractive route for the fabrication of catalysts for important industrial applications on a large scale.