Abstract: In the main part of this study an integrated three-phased methodology is developed to solve two problems of carrier selection and network flow assignment concurrently. In the first phase, after reviewing the existing literature, 5 groups of criteria that influence the carrier selection and evaluation are determined which are: cost, insurance of service provision, handling services, customer service and strategic compatibility. In the second phase, using AHP techniques and the criteria of the first phase, a weight factor is assigned to each carrier. Then in a multiple objective mixed integer linear programming model the flow of the product in the network and the amount of freight allocated to carriers are determined. The objectives are to maximize total value of freight allocation and to minimize the transportation and inventory costs. In the end the application of the methodology in the Middle East giant auto manufacturer IKCO is explained. This methodology proposes a step by step approach that is applicable in any other industry.