Warehouse layout and order picking are critical to warehouse management since companies try to follow the tendency of one-day shipping, the optimization of warehouse processes is vital for fulfilling customer’s needs. This paper proposes a change in a warehouse layout and the implementation of a Genetic Algorithm (GA) with objective of optimize the order picking operation in a textile industry, considering a real case scenario. The proposed GA uses sales data and data mining techniques to minimize the distance between the bestselling items. The obtained results have demonstrated the feasibility of this approach, supplying two optimal warehouse layout configurations with minimal distances between the top- selling items.