Flexible pavements can be enhanced with sustainable granular layers, such as cementitious stabilization or geosynthetic reinforcement, to improve their strength and thickness. However, the design should prioritize economical and sustainable solutions, using locally sourced materials, and adhering to Indian standards. This study aims to determine the optimal design of flexible pavements for National Highway (NH) 163, a case study located between Ghatkesar and Uppal in Hyderabad, adhering to the Indian Road Congress (IRC) provisions. Traffic volume and subgrade California Bearing Ratio (CBR) values were obtained for the study area. Initially, a conventional flexible pavement was designed, followed by the incorporation of cementitious treatment and geogrid reinforcement into the granular layers. A comparative analysis was conducted, focusing on performance and cost parameters. The findings reveal that cementitious treatment is cost-effective, whereas geogrids provide a sustainable option compared to conventional pavements. This study presents an optimal solution for engineers to design cost-effective and durable flexible pavements using locally available materials.