This study's subject is the effectiveness of substituting Thar Coal Fly Ash (TCFA) for ordinary Portland cement, also known as OPC. Tharparkar, Pakistan, possesses the world’s third largest coal reserves, with deposited coal fuel of 175 billion tons and capable of providing energy for over 200 years. Thar Coal is a lignite type that produces 7-10% of by-products in ashes; among them, Fly Ash is a significant waste. Reusing this waste as a partial cement replacement offers an environmentally friendly solution. This study prepared concrete specimens with varying proportions of TCFA (0%, 10%, 20%, and 30% by mass) as cement substitutes. Compressive strength tests were conducted on 36 cubes (100mm x 100mm x 100mm) with different fly ash percentages at a proportion to water to cement of 0.52. Ages 7, 14, and 28 days for curing were considered. The findings demonstrate that a higher TCFA component enhances the workability of the concrete. At all curing ages, the strength in compression at a 20% TCFA replacement level was greater than that of standard concrete. However, as the cement replacement was increased to 30%, there was a slight decrease in the comparative compressive strength compared to regular concrete. The tensile strength of the splitting test, performed after twenty-eight days of curing age, reveals that it surpassed conventional concrete for all replacement levels. Considering the favorable outcomes in workability, constrictive strength, durability strength, and substantial economic and environmental benefits, there is much potential for using TCFA as a cement substitute in the construction sector.