The aim of this study is to identify the various functions that English as a Lingua Franca (ELF) serves for both students and teachers in university classrooms of Greek as a second/foreign language (L2) in Greece. The research was conducted in the L2 Greek Erasmus + classes at the National and Kapodistrian University of Athens. A triangulation of methods was employed, including a questionnaire completed by students attending the Greek courses, qualitative interviews with the teachers of these classes, and nine hours of classroom observation. The findings reveal that, due to the multilingual environment and students’ low proficiency in Greek, English was frequently used to fulfill different functions in class. Specifically, ELF was extensively employed by both teachers and students for purposes such as explaining and translating vocabulary and grammar rules, giving instructions, and discussing sociocultural topics. Our study highlights the pedagogical aspects of translanguaging and supports the notion that students benefit from leveraging their linguistic repertoires in language classrooms, leading to a more effective and meaningful learning experience.