Purpose Unlike previous literature, this study offers a novel integrated fuzzy approach to the field of outsourcing decisions. The purpose of this paper is to use design ranges of evaluation criteria that satisfy the functional requirements (FRs) of decision makers to solve the outsourcing provider selection problem. Design/methodology/approach In this study, considering the expected significance of outsourcing evaluation criteria, and the FRs of decision makers expressed in linguistic terms, a robust multi-criteria decision-making (MCDM) tool based on the integrated use of fuzzy Step-wise Weight Assessment Ratio Analysis and weighted fuzzy axiomatic design methods is proposed for use in decision process. Findings The proposed method is applied to a Turkish chemical company. A sensitivity analysis is performed and the outcomes of the proposed integrated framework are compared with those of other MCDM methods such as fuzzy-based Technique for Order Preference by Similarity to Ideal Solution, fuzzy Vise Kriterijumska Optimizacija I Kompromisno Resenje and fuzzy Multi-Objective Optimization on the basis of Ratio Analysis. This validates the usefulness and practicality of the proposed methodology.