Universal Design for Learning (UDL) is considered to provide equitable opportunities for all learners with or without disabilities. This study aimed to examine the extent to which UDL was implemented in ESL classrooms at the university level. A mixed-method approach was conducted to explore the effective ways to maximise learning outcomes, inclusion, and equity regarding UDL principles; both students' and teachers' voices were addressed. Online questionnaires for students and semi-structured interviews for teachers were used to probe the UDL application in the classrooms. The findings revealed that teachers employed UDL principles in their classrooms to varying degrees. They also explored various strategies to enhance levels of engagement, representation, action, and expression. However, they experienced different tensions during the process. The study concluded with implications for researchers, teachers, and policymakers in developing a more inclusive and equitable learning environment.