<p>The accelerating depletion of petroleum reserves and the steep environmental cost of bitumen production have made traditional asphalt binders increasingly unsustainable for modern road construction. At the same time, global road networks continue to expand, deepening reliance on fossil-based materials and intensifying CO₂ emissions across the infrastructure sector. These pressures demand scalable, renewable binder alternatives that can simultaneously reduce carbon footprint, stabilize long-term material supply, and improve the environmental performance of pavements. Lignin, an abundant by-product of the pulp and biorefinery industries, has emerged as one of the most technically promising candidates for partial bitumen replacement due to its aromatic structure, intrinsic stiffness, and antioxidant characteristics. However, a multi-scale approach is required to fully evaluate the technical and environmental viability of integrating lignin into bituminous pavement systems. This review examines the chemical, rheological, and mechanical characteristics of lignin-modified bitumen, along with its performance in asphalt mixtures. Life-cycle analysis (LCA) and economic viability are assessed, followed by a statistical evaluation aimed at identifying the optimum type and dosage of lignin. The results indicate that wood lignin powder at a 10% bitumen replacement level offers the most favourable balance of technical performance and economic feasibility.</p>