Seawater batteries utilizing naturally abundant seawater as the cathode material offer economic advantages. Despite their versatility, they suffer from slow kinetics and high overpotential, limiting their efficiency. Addressing this, electrocatalysts emerge as crucial for enhancing performance. However, conventional electrocatalysts, primarily noble metals, are scarce and expensive. In this context, carbon materials derived from biowaste have garnered considerable attention. In this work, we employed lignin, the most abundant aromatic polymer, as a precursor for carbon materials, addressing the critical need for sustainable and efficient electrocatalysts in seawater batteries. To enhance the catalytic properties, we innovatively used urea - a compound typically associated with environmental challenges - for nitrogen doping. This approach allowed us to synthesize doped carbon catalysts that achieved performance metrics comparable to those of conventional Pt/C catalysts. Our findings not only demonstrate the potential of lignin and urea as effective electrocatalysts but also highlight a significant advancement towards enhancing the performance of seawater batteries. This opens new avenues for the development of sustainable energy storage solutions, leveraging biowaste materials to address environmental and energy challenges.