Multiple Criteria Decision Making (MCDM) methods have been widely used in literature with different extensions to handle uncertain information for years. The aim of this study is to propose an improved Complex Proportional Assessment (COPRAS) approach by integrating Interval-Valued Pythagorean Fuzzy Set (IVPFS) which is the extension of interval-valued intuitionistic fuzzy set (IVIFS) to deal with MCDM problems in the uncertain environment. It is evident from the previous studies in the literature, extension version of COPRAS method with IVPFSs is first proposed. In order to illustrate the applicability and accuracy of the proposed approach, a real-world application of selecting the optimal fiber optical access network strategy for Arnavutkoy district in Istanbul is presented. Sensitivity analysis is applied to examine the robustness of the proposed method. A comparative analysis of the proposed method with other existing methods is also conducted.