The purpose of this study was to look into teachers' perceptions of code-switching functions and effects in English as a foreign language classroom. In the study, a descriptive survey design and an interview were used to investigate the functions and effects of code-switching in English as a foreign language (EFL) classroom. 46 people responded to the survey questionnaire about code-switching functions and their impact in the classroom. Seven teachers participated in the group interview. The interview findings revealed six functions and four effects of code-switching. According to the survey findings, the majority of teachers supported the use of code-switching in their classrooms because it served a useful purpose in the process of teaching and learning English. The findings also revealed that teachers believed code-switching provided a clear purpose and had a positive impact on instruction and language development in EFL classrooms by creating a sociable environment. It was also demonstrated that code-switching to teachers was effective in EFL classrooms and played an important role in English learning and teaching. The implications of the findings for EFL teachers and language learning settings were discussed.