I discern that English as a global language owes its origins to colonialism whose power has markedly affected the entire world. Learning and teaching English in Thailand, an only country in Southeast Asia that withstands the menace of colonization, I neglected to take cognizance of the coloniality of power that had a bearing on my non-colonized country. I employ an analytic autoethnography as epistemology to investigate the extent to which the coloniality of power impacts my English language teaching and learning experiences in Thailand in the post-colonial epoch. I lean on linguistic imperialism as a main theoretical construct to frame my autoethnographic research. I explore the personal memories of my English language learning and teaching as well as other relevant artifacts. I interpret my assemblages through reflexivity and mindful approach to ethnography. The following insights gained bear testimony to the coloniality of power adhering to my experiences. My experiences in learning English are intertwined with the coloniality of power in several ways. I realize that my initial step toward learning English is interlocked with Christianity. In my schooldays, not only did I learn English, I also underwent the religious practices and cultures that belonged to the Western colonizers. Secondly, the supremacy of English over other foreign languages in Thai educational system indicates its hegemonic power and its role as a tool in service of neocolonialism. In addition, mastery of English entails the overarching structure of asymmetrical power relations and social hierarchies. Lastly, the Anglocentric dominance over my English language learning highlights the superiority of English as a British colonial lineage and seems to denigrate English as a global language that supports an equal variety of Englishes. As regards my English language teaching experiences, my critical examination reveals the colonial construction of the native-speaker Self as superior Center and the non-native-speaker Other as inferior Periphery. I acknowledge that I legitimize my self-marginalization. In addition, my utilization of Western published materials accentuates the monolingual and monocultural tenet that perpetuates linguistic imperialism. Furthermore, my experiences in a colonial-celebratory environment uphold the superior merits of English as a colonial legacy. Finally, my attempts to create the English monolingual classroom environment demonstrate that my ideological stance is dominated by colonialingual ideologies and linguistic imperialism. I argue that my learning and teaching of English in my non-colonized country have indissoluble links with colonialism. Patently, they perpetuate the coloniality of power. My autoethnography raises a critical awareness among Thai teachers, scholars, educators, researchers, and stakeholders of the invisible coloniality of power and its impact that are seemingly overlooked by Thai people. It has profound implications for the decolonial future of English language education in Thailand.