There is a paucity of research about and done by L2 Chinese educators regarding the theoretical construct of agency. It is also noted that the qualitative inquiry is marginalized in L2 Chinese research field, let alone the narrative study of the agency of experienced by L2 Chinese-teachers. In this dissertation research, I aim at filling in the gap by conducting a longitudinal autoethnography which captures over a decade (1997-2017) of my personal and professional development with an agency perspective. The highly personalized autoethnographic accounts open up my personal and professional life as an experienced, college-level, transnational, early 40's female native Chinese teacher from mainland China. Using socio-cultural sensibilities and ecological approach of agency to scrutinize the paradigm shifts and behavioral changes over extended periods of time, I strive to make visible my active sense-making of affordances and constraints of diverse societal and educational surroundings in Indonesia, the US, China and the US again. I hope to exam the personal world and intellectual, professional trajectory over a long time to extend readers' sociological understanding (Sparkes, 2000) of the rich and complex life of a language teacher. The critical reflexive analysis, deep reflection, and writing as analysis inquiry of my own transformations are demonstrated in multiple shifting identities over time and across different milieu, from English as a foreign language teacher, to Chinese as a second language teacher within China and to Chinese as a foreign language teacher outside Chinese-speaking context, from a teacher-researcher, teacher mentor, teacher educator, to a lifelong teacher-learner. The manifestations of various forms of agency-as-achievements and the evolvement of agency-as-capacities have also been examined. One of the main impetuses of this autoethnographic project is creating an alternative narrative of a nonconformist so as to challenge the existing stereotypical narratives of Chineseness in work-abroad native-speaking China-born teachers as well as traditional development trajectory of language teachers. My concrete experiences as a transcultural, bilingual, and bicultural (L1 Chinese, L2 English) language educator together with intellectual biography exhibit a unique personal, scholarly and professional growth in a postmodern, globalized, multicultural era through various social identities and evolving agency development. Using the power of autoethnography, I make explicit the multiplicity of self-representation and critically self-reflective learning about agency. This work hopes to inspire reflective and reflexive practices in other L2 educators, especially experienced in-service language teachers, to destabilize their ideologies and beliefs regarding L2 education and reflective practice, to educate their attention to social aspects of language learning and teaching, and to humanized language education. Ultimately, readers are encouraged to move into action to explore the notion of agency and use the power of autoethnography in language education and on language education.