Information Technology(IT) plays a pivotal role in building corporate competitiveness and ensuring business performance, and can help attract investment. Global economic uncertainty, however, as well as recession spotted in between, compel companies to lower their IT spending and seek alternatives while trying not to compromise quality. This has led to the fast-paced growth of IT Outsourcing(ITO), or the assignment of a business function or process including IT that supports it to an external party. In this sense, professional expertise and domain knowledge are highly valued as companies recognize the importance of choosing a most optimal outsourcing provider. This, in turn, fuels cutthroat competition among IT service providers to land projects given the pressure for cost savings the providers face.\nFactors affecting choice of service providers were pinpointed via theoretical consideration using a multi-criteria decision-making(MCDM) method, as well as in-depth interviews with IT service professionals. This led to the development of a model for the Analytic Hierarchy Process(AHP), consisting of 5 criteria and 17 sub-criteria. Furthermore, IT service professionals with 10 or more years of experience were interviewed in person to perform an empirical analysis using the data collected.\nBased on the empirical analysis, this study deduced weighted values pertaining to the identified factors. One key finding was the relative importance of factors differed by segregated group depending on the IT service type. Another discovery was that factors with higher priority were applied in a strategic and discriminative manner depending on situational characteristics.