<p>This qualitative study is aimed at investigating the transition to English as the medium of instruction in Moroccan Higher Education (HEIs) by exploring lecturers’ perspectives from two different disciplinary backgrounds: business administration and medicine. Data were collected through semi-structured interviews with 20 lecturers and analysed using grounded theory methodology techniques. Four overarching themes emerged from the data: (1) English as a decolonial language, (2) transitioning to EMI in Moroccan higher education institutions, (3) development of disciplinary literacy, and (4) perceived impact on students’ academic performance. Lecturers viewed English as a means of linguistic decolonization and as a tool for students’ academic and professional advancement. They also considered the new EMI environment favourable for students’ literacy development and content learning. However, participants also highlighted some challenges that may hinder broader transition to EMI in Moroccan HEIs, particularly limited English proficiency among students and lecturers, and a lack of training for EMI lecturers. The study ends with implications to promote the EMI initiative in Moroccan education.</p>