This paper proposes a new smart supervisor controller (SSC) for load frequency control (LFC). The smart supervisor controller makes a smart selection between two different controllers to combine the advantages of each one. There are some controllers are simple for implementation such as proportional-integral (PI) controller but may have some drawback when the complexity in the system increases. This drawback may be due to the design method of gain selection of the PI controller. The design method may make the PI controller reduces the maximum overshoot of the system response but the settling time increases. In contrary, another different design method may make the PI controller reduces the settling time of the system response but the maximum overshoot increases. The proposed SSC makes a smart selection between the different PI controllers based on the advantage of each design method which can add it to the system. A two-area interconnected power system is considered to realize this study. Simulation results confirm on the better performance of the proposed SSC compared to the genetic algorithm (GA)-based PI controller and bacterial foraging optimization algorithm (BFOA)-based PI controller over a wide range of load changes and system parameters uncertainties.