["European Journal of Education, Volume 61, Issue 3, September 2026. ", "\nABSTRACT\nSustainability education (SE) is increasingly recognized as a critical aspect of higher education and teacher education due to global environmental, social, and economic challenges. However, limited research has examined how teacher educators in developing countries, including Iran, conceptualize and implement sustainability in their teaching practices. This qualitative narrative study explored how Iranian English as a Foreign Language (EFL) and Social Science (SS) teacher educators interpret and enact sustainability through the Identity–Agency–Disciplinary (IAD) framework. Twenty semi‐structured interviews were conducted with teacher educators from four public universities in Iran, and thematic analysis was performed using NVivo software. Findings indicate a complex, recursive relationship between sustainability literacy and sustainability implementation. EFL teacher educators exhibited strong awareness of sustainable practices' outcomes but reported limited integration of sustainability into their professional identity, enacting only partial sustainable practices. Conversely, SS teacher educators demonstrated conceptual understanding of sustainability but experienced identity fragmentation and resistance to practical implementation. Across both disciplines, identity tension and constrained professional agency exceeded institutional constraints, while disciplinary culture both facilitated and hindered transformative practices. Overall, the study reconceptualizes teacher educators as conditionally empowered actors who implement sustainability only when identity, agency, and disciplinary culture align. These results highlight that effective sustainability reforms in teacher education require systematic support for professional identity development and opportunities for agency, rather than reliance solely on policy mandates. This study contributes to literature on teacher identity, professional agency, and disciplinary culture, offering theoretical and practical insights for fostering transformative, sustainability‐oriented pedagogical practices in diverse educational contexts.\n"]