One of the most challenging aspects associated with retaining walls is water accumulation behind them and its detrimental effects on wall stability. Water infiltration and seepage cause an increase in pore water pressure, reduction of effective stress and shear resistance of soil, and can lead to wall failure. In this study, the performance of several types of drainage systems, including in-wall drainage, vertical drainage, inclined drainage systems at angles of 0°, 30°, 45°, and 60° to the horizontal, and drainage beneath the foundation, in controlling seepage and improving the factor of safety of cantilever concrete retaining walls using numerical modeling were investigated and compared with the case without drainage. The study was conducted under two geometric conditions, including level ground behind the wall and sloped ground with an angle of 20°. The results showed that vertical drainage exhibited the best hydraulic performance in seepage control, while horizontal drainage at the wall base provided the greatest improvement in the overall stability factor of safety. Additionally, drainage beneath the foundation performed better in preventing overturning, and 30°inclined drainage showed superior performance in controlling sliding. The comprehensive results of this research demonstrated that a combined approach of seepage and stability analysis is the best tool for selecting appropriate drainage, and in practice, can prevent failures of retaining walls.