This paper presents a modified design of a sliding mode controller based on fuzzy logic for a dc-dc boost converter. Here a proportional - integral (PI)-type current mode control is employed and a sliding mode controller is designed utilizing fuzzy algorithm. Sliding mode controller ensures robustness against all variations and fuzzy logic helps to reduce chattering phenomenon introduced by sliding controller, thereby increasing efficiency and reducing error, voltage and current ripples. The proposed system is simulated using MATLAB/SIMULINK. This model is tested against variation of input and reference voltages and found to perform better than conventional sliding mode controller.