Glass fiber-reinforced polymer (GFRP) bars are gaining prominence as a sustainable alternative to traditional black steel reinforcement, offering advantages such as high strength-to-weight ratios and corrosion resistance. While previous studies have explored the economic and environmental benefits of using GFRP bars instead of steel, the corrosion-resistant nature of GFRP significantly reduces long-term maintenance and replacement costs. Additionally, the lightweight nature of GFRP bars reduces transportation and handling expenses, enhancing their cost efficiency. From an environmental perspective, GFRP bars contribute to a reduced embodied carbon footprint compared to conventional steel. This study evaluates the use of GFRP and steel bars across six diverse infrastructure projects in Saudi Arabia, including flood channels, bridge decks, sidewalks, and slabs on grade. The analysis considers material and concrete costs, embodied carbon emissions (kg CO₂e/kg material), and structural performance. Local supply chain data, including a regional GFRP manufacturer's environmental product declaration (EPD), were used to ensure contextual accuracy. The findings reveal that replacing steel bars with GFRP bars may reduce total embodied carbon by up to 72% and total construction costs by 13%, primarily due to lower transportation, handling, and maintenance requirements. However, embodied carbon values vary depending on regional production methods and material sourcing. Additionally, the analysis highlights the positive environmental impact of GFRP bars, which contribute to significantly lower carbon dioxide emissions compared to steel. This study highlights the potential benefits of GFRP reinforcement in reducing environmental impacts and lifecycle costs, particularly in regions exposed to aggressive environmental conditions.