The integration of blended winglets in modern aircraft design offers substantial aerodynamic advantages by reducing induced drag and enhancing lift-to-drag ratio. This research focuses on the design, simulation, and optimization of a blended winglet for a NACA 2.5411 airfoil using Reynolds- Averaged Navier- Stokes (RANS)-based Computational Fluid Dynamics (CFD) simulations. The airfoil geometry was modeled in SolidWorks and meshed using ANSYS Fluent with a fine structured grid near the boundary layer to ensure accurate flow resolution. Steady-state simulations were conducted under subsonic flow conditions at Reynolds numbers corresponding to typical cruise speeds. The velocity and pressure contours, along with lift coefficient and lift force data, were analysed to quantify aerodynamic efficiency. The results demonstrated a significant reduction in wingtip vortices, resulting in enhanced lift generation and reduced induced drag. Velocity streamlines confirmed smoother flow distribution around the winglet junction, indicating improved aerodynamic stability. The optimized blended winglet design achieved an increase in lift coefficient by approximately 8- 12% compared to the baseline configuration without winglets. This study validates the role of RANS-based CFD in optimizing winglet geometries, providing a computationally efficient approach for sustainable aerodynamic design improvements applicable to next-generation aircraft.