<p>Infill walls are essential in all types of buildings as they reduce the effect of lateral forces. Many materials, such as bricks, stones, hollow core blocks, precast blocks, and fly ash bricks, are used in infill walls. This study aims to develop an eco-friendly, sustainable, and durable interlocking brick. Geopolymer bricks were preferred in this regard to impart the eco-friendly effect, as geopolymers have low embodied carbon. Industrial wastes such as ground Granulated Blast Furnace Slag (GGBS) and coir fibers were used to induce sustainability. The geopolymer binder was made using GGBS and activator solutions: sodium hydroxide (NaOH) and Sodium Silicate (NaSi₂O₃). Geopolymer interlocking earth blocks of size 9″ × 8″ × 5″ were made, and the GIEB mix's proportions consisted replacement of red soil with GGBS at 0%, 5%, 10%, 15%, 20%, 25%, with constant fiber addition of 0.5% in the soil. The tests conducted for interlocking blocks include dry and wet compressive strength, water absorption, and ultrasonic pulse velocity tests. From the experimental investigation results, it was observed that the strength gains of about 20% were obtained by GGBS and fiber additions. Mix with 20% GGBS and 0.5% coir fiber showed higher strengths of 28.03&#xa0;MPa and 19.02&#xa0;MPa in the dry and wet states, respectively. It was also found that the embodied carbon and embodied energy values were lower for the GIEB compared with the conventional blocks.</p>