In this study, the Grey Wolf Optimization (GWO) based maximum power point tracking (MPPT) algorithm with a single-ended primary-inductor converter (SEPIC) converter is proposed for solar photovoltaic (PV) systems. SEPIC converter which has voltage step-up and step-down capability removes the non-operational zones related about the input voltage. The PV module current and voltage are used as inputs of the GWO based MPPT algorithm. It determines the duty cycle of the converter and controls the operating point to track the maximum power point for any operating condition. Proposed system is designed and simulated in MATLAB/Simulink to test its performance for different operating conditions. Simulation results have proved the fast response and improved steady state performance of proposed MPPT method and SEPIC converter.