Recently, emerging functions utilizing phenolic molecules, such as surface functionalizing agents or bioadhesives, have attracted significant interest. However, the most important role of phenolic compounds is to produce carbonized plant matter called “coal”, which is widely used as an energy source in nearly all countries. Coalification is a long‐term, high‐temperature process in which phenols are converted into conducting carbonized matter. This study focuses on mimicking coalification processes to create conducting sealants from non‐conducting phenolic compounds by heat treatment. We demonstrate that a phenolic adhesive, tri‐hydroxybenzene (known as pyrogallol), and polyethylenimine mixture initially acts as an adhesive sealant that can be converted to a conducting carbon sealing material. The conductivity of the phenolic sealant is about 850 Ω⁻¹ cm⁻¹, which is an approximately two‐fold enhancement of the performance of carbon matter. Applications of the biomimetic adhesives described herein include conducting defect sealants in carbon nanomaterials and conducting binders for metal/carbon or ceramic/carbon composites.