The construction industry worldwide is under increasing pressure to transition towards sustainable practices and reduceit relies on conventional clay-fired masonry units. The production of traditional burnt clay bricks contributes heavily to topsoilerosion, deforestation, and atmospheric pollution due to high-temperature kiln firing. This research presents a thoroughexperimental investigation into the development, optimization, and structural evaluation of unfired eco-friendly bricks producedfrom industrial byproducts, specifically fly ash, lime, black sand, fine gravel, and minimal cement binder. By evaluating physicalcharacteristics including specific gravity, particle size distribution, matrix compaction, water absorption, density, and multi-stagecompressive strength development up to 56 days, this study establishes an optimized mix design. The baseline compositionconsisting of 50% Black Sand, 20% Gravel, 10% Lime, 10% Cement, and 10% Fly Ash compressed at high forming pressuresachieves superior 28-day compressive strengths exceeding 110 kg/cm² and long-term strength exceeding 16 MPa, while satisfyingIS code standards for structural masonry.Keywords: Fly ash, Black sand, Unfired eco-bricks, Compressive strength, Water absorption, Pozzolanic reactivity, Wasteutilization, sustainable infrastructure.