In the Anthropocene era, which is marked by rapid environmental, technological, and sociocultural transformations, L2 teachers are frequently called upon to demonstrate psychological adaptability, intellectual humility, and intercultural sensitivity. Central to such adaptive expertise is teachers’ open-mindedness, a dispositional capacity to engage with diverse perspectives, question entrenched assumptions, and embrace pedagogical change. Guided by Bronfenbrenner’s nested ecosystem model, this phenomenological study explored the predictors of L2 teachers’ open-mindedness across multiple ecological layers of their professional lives. Data were collected through semi-structured interviews and autobiographical narratives from 54 L2 teachers working in diverse instructional settings, including schools and universities. Thematic analysis revealed that teachers’ open-mindedness is shaped by a dynamic interplay of microsystem (student diversity, student feedback), mesosystem (collegial interactions, institutional support, organizational culture), exosystem (educational policies and guidelines, parental expectations), macrosystem (cultural norms and values, societal expectations), and chronosystem factors (teaching experience, rapid changes in instructional tools). Together, the findings highlight that teachers’ open-mindedness is not a fixed personality trait but a dynamic, context-sensitive disposition, continually influenced by various ecological elements. The findings offer actionable insights for educational administrators, policymakers, and teacher trainers seeking to cultivate open-mindedness among teachers.