<p>Despite centuries of advancement, the synthesis of carbon materials remains heavily reliant on energy-intensive thermal processes. Conventional methods require external heating for prolonged periods to overcome high energy barriers, posing challenges for sustainable large-scale production. Here we show an energy-autonomous synthesis pathway that utilizes the intrinsic chemical energy stored within a polyaniline-HClO₄ composite. Triggered by mild thermal, microwave, or mechanical stimulation, the precursor undergoes a rapid exothermic self-propagation driven by the explosive decomposition of perchlorate species. This single-step process, completed in ≈0.4 s, simultaneously generates intense localized heat and a massive volume of gas, which forcibly exfoliates and carbonizes the polymer into interconnected 2D amorphous carbon nanosheets. We demonstrate that this energy-efficient method achieves carbon conversion efficiencies comparable to traditional pyrolysis. Furthermore, the reaction intensity is precisely tunable via the precursor water content, ensuring potential for safe industrial scale-up. This approach also enables the atomic-level incorporation of transition metals, creating a versatile platform for the design of catalysts for oxygen and carbon dioxide reduction reactions. This work provides a scalable, energy-autonomous pathway for carbon synthesis and offers a platform for the precise construction of catalytic architectures.</p>