Since its emergence, the concept of sustainability has been incorporated in geography education across the globe. China is no exception. As one of the pioneer countries in advocating environmental protection, the Chinese government has called for a paradigm shift in pedagogies in order to encourage students to effectively learn the concept and develop their ability to think in new ways, especially engaging themselves with contemporary worldviews. However, many teachers may feel that they are incapable of teaching sustainability. Therefore, it is important to examine whether subject teachers have the ability to implement sustainability education. To fill this research gap, the present research focused on a case study of an in-service Chinese geography teacher teaching sustainability in a junior middle school in China. In order to deeply understand his teaching, this research adopted the form of interviews, supplemented by the analysis of relevant teaching documents. The results indicated that the two themes taught in the seventh and eighth grades, respectively, involved mainly environmental sustainability with some connection to economic sustainability, but fell short of socio-cultural sustainability. This study calls for more sustainability elements in geography curriculums, particularly with the inclusion of socio-cultural sustainability. In this article, research and practical implications have been given.