Water production remains a significant challenge in the oil and gas industry, as it can severely impact operational efficiency and economic feasibility. Excessive water production not only reduces oil recovery but also complicates field development. This study presents the development and field application of a novel in-house nanosilica fluid system specifically designed to mitigate water production in oil wells. Through comprehensive laboratory testing and field adaptation, key parameters such as activator concentration, temperature, gelation time, and pumping rates were optimized to achieve maximum efficiency. The scientific value of this work lies in its innovative use of nanosilica to provide a more controlled and adaptable solution to water management challenges, offering distinct advantages over traditional methods. Field results demonstrated a substantial reduction in water production and enhanced oil output, validating the nanosilica system's effectiveness. This approach reduces operational risks and costs and eliminates post-treatment complications, positioning nanosilica as a promising and flexible tool in water shutoff applications.