The increasing demand for sustainable solutions in road infrastructure highlights the need to develop innovative approaches for incorporating waste materials into asphalt pavements. Given the high material consumption of road pavements, their potential for waste valorisation is considerable, particularly through bitumen modification with polymers. One of the most promising materials in this context is polyurethane, widely used in footwear manufacturing but often discarded in landfills at the end of its lifecycle. This study investigates the feasibility of using polyurethane waste as a bitumen modifier to enhance asphalt performance while reducing environmental impact. Bitumen was modified with 3% and 5% polyurethane, and its properties were evaluated through penetration, softening point, dynamic viscosity and rheology tests, comparing conventional and modified bitumen. The results indicate that adding 3% polyurethane improved the bitumen’s mechanical performance significantly, particularly the rutting resistance at high temperatures, suggesting that polyurethane-modified bitumen could be a viable alternative for more durable and sustainable road pavements. This approach contributes to circular economy principles and offers a potential solution for the disposal of footwear waste. Further studies should assess long-term pavement performance and field applicability.