This study investigates the perceived challenges experienced by English teachers in implementing Differentiated Instruction (DI) as mandated by the Kurikulum Merdeka at MAN 6 Aceh Besar. Differentiated Instruction, which aims to address students’ diverse readiness levels, interests, and learning profiles, is a core strategy within the student-centered framework of the new curriculum. Despite its potential to improve educational inclusivity and learning outcomes, the implementation of DI faces several obstacles in real classroom settings. Using a qualitative descriptive method, this research involved semi-structured interviews with three English teachers. Thematic analysis of the data revealed that the main challenges include limited understanding and training on DI, time constraints in lesson planning and delivery, inadequate learning resources, and student misconceptions about fairness. Teachers also noted a gap between the theory of DI and its practical application. To overcome these challenges, the participants emphasized the importance of continuous professional development, collaboration among teachers, administrative support from schools, and access to varied learning materials. This study contributes to a better understanding of how differentiated practices can be more effectively supported and implemented in Indonesian classrooms, particularly within the framework of Kurikulum Merdeka.