<p>Non-isocyanate polyurethanes (NIPUs) have emerged as a sustainable alternative to conventional polyurethanes, primarily due to their synthesis pathway, which eliminates the use of toxic isocyanates. In parallel, the incorporation of functional fillers to impart electrical and thermal conductivity to otherwise insulating polymer matrices has gained significant attention, enabling advanced applications in heating, sensing, and energy systems. In this study, aminated soda lignin was employed as the sole amine source to synthesise lignin-based NIPUs, while graphite was incorporated as a functional filler to induce surface anisotropy. The NIPU formulation was first optimised by evaluating catalyst activity and varying the aminated lignin content, demonstrating tuneable mechanical and thermal properties. The subsequent incorporation of graphite (1–10 wt%) led to the formation of Janus-type polymer sheets, in which the filler’s gravitational settling produced a conductive bottom surface and an insulating top surface. At 5 wt% graphite loading, the composite exhibited an electrical conductivity of 863 µS cm^− 1, reaching the threshold required for strain-sensing applications while maintaining an elongation at break of 15%. The composite displayed a low cross-plane thermal conductivity of 0.237&#xa0;W m^− 1 K^− 1, high thermal stability (268&#xa0;°C), and differential temperature response, highlighting its suitability for integration into heating-related applications. To the best of our knowledge, this is the first report of lignin-based NIPU Janus materials, offering a potentially sustainable strategy for the development of multifunctional polymer films suitable for low-temperature flexible heaters and wearable sensors.</p> Graphical abstract <p></p>