This study explores the impact of code-switching on classroom interaction in English lesson, with a focus on both teachers' and students' use of multiple languages in the classroom. The research is conducted at MAN Aceh Singkil and employed a qualitative descriptive method, utilizing observations, interviews, and audio documentation to analyze the types and impacts of code-switching during English lessons. The findings reveal that Intra-Sentential Switching is the most frequently used type, followed by Inter-Sentential Switching and Tag-Switching. Student interviews show a generally positive perception of code-switching, indicating that it helps them to better understand lesson content, enhances vocabulary acquisition, and boosts confidence in using English. However, some students particularly male students reported occasional confusion or hesitation when engaging in code-switching. Despite these challenges, code-switching is shown to facilitate a more inclusive and effective learning environment. The study concludes that strategic and mindful application of code-switching can support language acquisition and improve classroom interaction, also highlighting the need for teachers to adapt their teaching to students’ diverse linguistic backgrounds.