<p>India’s rapid growth in road infrastructure, as evidenced by its road network being ranked second globally, is pressing the demand button for natural aggregates, the availability of which is becoming increasingly scarce. To address this growing concern, the application of geosynthetics, such as geogrids and geotextiles, offers an innovative solution for sustainable pavement construction. This study investigates the performance of geosynthetics in flexible pavements built over subgrades with California Bearing Ratio (CBR) values between 6 and 10%. Large-scale laboratory tests were carried out utilizing biaxial geogrids (PP30 and PET80) for base layer reinforcement and a 200 GSM geotextile for subgrade stabilization. The performance of the geogrid-stabilized pavements was assessed using the Modulus Improvement Factor (MIF) and Layer Coefficient Ratio (LCR) based on the guidelines from AASHTO (1993), IRC37:2018, and IRCSP59:2019. The results demonstrated that geogrid-reinforced pavements significantly reduced granular layer thickness compared to unstabilized pavements. Carbon footprint reductions were observed between 13 and 21% across the different CBR conditions considered. Among the tested cases, the CBR 6% subgrade reinforced with PET80 geogrid exhibited the highest carbon footprint reduction. In addition to environmental benefits, the study demonstrated that geogrid-reinforced pavements resulted in cost savings ranging from 14 to 24%. The greatest cost reduction was achieved with PET80 geogrid on a 6% CBR subgrade, demonstrating its superior performance in reducing material requirements and associated costs. These findings highlight the potential of geosynthetics to improve pavement performance, reduce environmental impact, and lower construction costs, positioning them as a critical component of sustainable road infrastructure development in India and similar regions, particularly in regions with weaker subgrade conditions.</p>