The aim of this paper is to understande the professional role of urban planners in confronting the complexities and conflicts within the process and environment of metropolitan planning in Tehran. Professional self-awareness among urban planners about their role is considered a key component in effectively understanding, explaining, and executing urban planning tasks. It is influenced by a set of individual, organizational, institutional, political, and discursive factors and plays a significant role in shaping the planners' approach to addressing urban complexities. The main question of this research is: How do urban planners of Tehran's metropolitan area perceive their professional role in addressing the complexities and conflicts within the planning process and its environment? In line with the objective of this research, the Constructivist Grounded Theory (CGT) method has been employed to focus on the planners' subjective constructions from an emic or introspective perspective. Following a systematic review of the literature and conducting semi-structured interviews with 18 planners experienced in the metropolitan planning environment of Tehran, the stages of initial, focused, and theoretical coding (comprising 225 initial codes and 33 conceptual categories) were completed to finalize the conceptualization based on the central category. The findings indicate that "professional self-awareness of planners in the field of roles" is the concept shaping the institutional behavior of planners, which plays a crucial role in understanding the geography of agency among metropolitan planners in Tehran.