Applications of the boost DC-DC converters are becoming popular due to their conformity to renewable energy systems. PI controllers are the most used controllers in power electronic circuit and systems controlling. This paper presents the optimal tuning of Proportional-Integral (P-I) controller for DC-DC boost converters based on Cuckoo Optimization Algorithm (COA). The COA based optimization of boost converter is modeled and simulated in MATLAB/Simulink environment under variable load. Then the simulation results of the COA based tuned PI controller are compared to the classical PI tuning method. The performance of proposed COA based tuning PI was better than conventional PI tuning method.