This paper formulates the sustainable smart grid systems' performance evaluation problem as a multicriteria group decision making problem and presents a new multicriteria group decision making approach for effectively evaluating the sustainable performance of smart grid systems. Intuitionistic fuzzy numbers are used for representing the subjective assessments of the decision makers. To greatly reduce the cognitive demanding on the decision makers, the pairwise comparison technique is adopted. An intuitionistic fuzzy weighted average (IFWA) operator is introduced for aggregating the intuitionistic fuzzy decision matrices into the overall intuitionistic fuzzy performance values. The concept of ideal solutions is applied for calculating the closeness coefficient value for every alternative across all criteria. An example is presented for demonstrating the applicability of the approach for dealing with sustainable smart grid systems' performance evaluation problems.