This paper presents the exploratory results of a case study analysis of the implications of global Englishes for senior high school English education in Taiwan. In response to the expanding contexts and uses of English, the current English curriculum in Taiwan's 12-year Curriculum for Basic Education calls attention to the global nature of English, which involves extended ownership and the acknowledgment of variations in English (Taiwanese Ministry of Education, 2018). However, the extent to which senior high school English teachers' cognition and practices reflect the spirit of the new curriculum is unclear. A qualitative approach was used in this study to record classroom observations and interview data from three teacher participants selected for their availability. The data were then analyzed and interpreted against global Englishes and teacher cognition literature. This study concludes that despite a general awareness of global Englishes, inconsistencies and paradoxes persisted within and between the participants' cognition and pedagogical practices along a continuum of traditionally to globally oriented English language teaching. Based on these findings and discussions, alternatives are proposed to complement senior high school English teaching in Taiwan.