There is a need for an efficient and rational multi-criteria group decision making (MCGDM) method to handle situations, in which decision makers from different domains or interested parties are involved in the vague and uncertain decision making processes. Thus, the research purpose of the study was to propose a vague set based MCGDM, which is easily understandable and simple computation to group decision members for handling vague and uncertain decision making processes. The MCGDM method is considered to be an umbrella under which a collective vague value solicitation and aggregation method as well as a numerical transformation method are included. Following the algorithm described in the proposed MCGDM method, an efficient polling method can contribute to soliciting group importance vague values and group performance vague values of alternatives. Besides, the solicited importance and performance vague values were aggregated by using a weighted aggregation function. Furthermore, a new score function can contribute to transform the aggregated vague values into comparable numerical scores for further decision making. Finally, a numerical case study was also conducted to demonstrate that the proposed MCGDM method is efficient and rational to solicit and aggregate vague values as well as to transform aggregated vague values into comparable numerical scores for decision making.