Information technology outsourcing provides several advantages for organizations, such as reducing the cost of ownership of IT products/services, providing rapid access to modern technologies. However, when the outsourcing relationship is not managed effectively, the desired results are not always achieved. This article aims to reveal the role of contract and relationship norms in the success of the IT outsourcing relationship, by focusing on the Turkish domestic market. Firstly, the measurement scales of the research were developed by making use of the previous studies and field interviews. Then the measurement model and hypotheses were tested using the partial least square method. It was concluded that both contract and relationship norms affect IT outsourcing success, but the contract is more effective than relationship norms for IT outsourcing success. Furthermore, it is concluded that relationship norms have a mediating effect between the contract and IT outsourcing success.