The paper presents a fuzzy extension of CODAS (COmbinative Distance-Based ASsessment) method which is called as interval-valued Atanassov intuitionistic fuzzy CODAS (IVAIF-CODAS) method for group decision making processes. The extended method considers interval-valued Atanassov intuitionistic fuzzy sets (IVAIFSs) to define the judgements of decision-makers and uses interval-valued Atanassov intuitionistic fuzzy weighted aggregation operator to aggregate the evaluations of decision makers. Due to the abilities of IVAIFS in modeling of uncertainty, the extended method can be readily applied to many decision problems under fuzzy circumstances. In the study, a personnel selection problem is handled to show applicability of the IVAIF-CODAS method. Computational analysis is performed by using three different well-known IVAIF-based multi criteria group decision making (MCGDM) methods in order to test the stability and validity of the outputs. The proposed method is an easy to use and an effective tool in terms of producing as robust results as other methods and requiring relatively less effort.