The current study explores the incorporation of electronic waste plastic (e-waste) as a partial substitute for river sand in ultra-high-performance concrete (UHPC) production. Addressing the pressing issues of resource depletion and e-waste management, the research investigates various e-waste plastic proportions in UHPC mixes to determine optimal levels for maintaining or enhancing mechanical properties. Comprehensive testing evaluates Flexural Strength (F-S), Compressive Strength (C-S), and Split Tensile Strength (S-T-S) at different curing ages. Microstructural analysis using optical microscopy assesses the effect of electronic waste plastic on concrete’s internal structure, while workability is measured through slump flow tests. The study aims to develop sustainable construction materials by recycling e-waste plastic while potentially improving UHPC performance. This innovative approach seeks to reduce dependence on natural resources, particularly river sand, and minimize the impact of concrete production on the environment. By aligning with sustainable construction practices and circular economy principles, the research contributes to the advancement of eco-friendly construction materials. The findings offer valuable insights into the feasibility of e-waste plastic incorporation in UHPC, promoting environmentally conscious infrastructure development and addressing the dual challenges of waste management and sustainable construction.