Nowadays, organizational decisions are made collectively in decision groups to achieve more meaningful and impactful outcomes, ranging from product design, policy and strategy formulation and resource allocation. This research, therefore, suggests a group decision-making (GDM) approach utilizing a recently developed MCDM method known as best-worst method (BWM) in combination with GIS for planning suitable areas for new emergency facilities in Istanbul. Using two decision-maker (DM) groups consisting of academic-related professionals and fire brigade practitioners, the BWM method was used to evaluate the associated weights and preference rankings of six pre-selected criteria, derived from pairwise comparisons of the best and worst criterion for each DM. The preference criteria of the two DM groups were examined to deepen the understanding of the varying perceptions about the level of influence of the criteria from a theoretical and practical view as well as to reflect a real-case scenario in typical GDM problems where group agreement or reliability is assessed by consensus using Kendall's coefficient of concordance,W. The BWM results were compared for model validation with the AHP and found to be reliable and consistent. Further, from statistical tests conducted, it was inferred that criteria C-4(density of hazardous materials) and C-1(high population density) were perceived to be the most important by the academician and fire brigade practitioner DM group, respectively. For both DM groups, criterion C-6(distance from earthquake risk) was viewed to be the least important. Resultant raster suitability maps for both DM groups were produced for visualizing the BWM model.