The sudden increase of numbers in terms of international students in once-monolingual EFL classrooms in Türkiye brought new challenges and opportunities for English as Foreign Language (EFL) instructors to adapt more culturally diverse setting-friendly approaches and methods in class instantly, which inevitably caused shifts and highlights on in-class practices as well. For this qualitative descriptive study, the data was collected from individual face-to-face interviews and survey results from eight experienced EFL instructors working at a Turkish private university's English preparatory program in the fall semester of the academic year of 2022-2023, focusing on highlighting the challenges and opportunities of teaching in multicultural classrooms. In conjunction with that, teachers' experiences with multicultural students were highlighted in teaching such interculturally and linguistically diverse settings. Following the manual thematic analysis of the data, results were grouped under three categories such as cultural, pedagogical and social issues regarding teaching in intercultural classrooms and presented in accordance with the relevant literature review which is in line with the results of this study. This paper contributes to this relatively new area of research as being one of the initial studies focusing on tertiary-level EFL instructors' experiences of teaching in multicultural classroom settings and their experiences rather than beliefs while teaching in such classrooms, and it can help to pave the way to design professional development activities which is crucial regarding aiming at improving Turkish EFL teachers' intercultural awareness in the classroom.