The rapid transformation of English linguistic landscapes has introduced the world to newly emerging English varieties or World Englishes, which are not typically employed in the Inner Circle. To address the defying phenomenon, this qualitative study explored the perceptions of Thai university lecturers on World Englishes, Thai English and the feasibility of implementing World Englishes and Thai English in the classrooms. Data were collected from semi-structured interviews with 15 English lecturers in 5 universities across the Thai regions. Analyzed by content analysis, findings revealed that the participants demonstrated mixed perceptions. While most of the participants viewed British and American Englishes as representations of standard English varieties and questioned the legitimacy of World Englishes and Thai English, others reportedly recognized and accepted the existence of World Englishes and considered Thai English as a tool to convey Thai identities and cultures. The findings also indicated that most participants outright disapproved of World Englishes and Thai English in teaching practices, and these varieties were substantially marginalized and devalued. However, to prepare learners for realistic use of English and increase their awareness of World Englishes and Thai English, the remaining participants suggested that English language teaching should embrace flexible linguistic conventions that allow spaces for Inner Circle, Outer Circle and Expanding Circle Englishes.