This research paper explores the effectiveness of Metacognitive Strategy Instruction [MSI] in enhancing the listening skills and autonomy of adult EFL learners in the advanced level of university preparatory studies in Oman. Utilizing a quasi-experimental design, the study involved an Experimental Group [EG] and a Control Group [CG], each comprising 24 students. The EG received MSI, while the CG did not, allowing for a comparative analysis of their listening performances and metacognitive strategy awareness. The study employed a mixed-method approach, incorporating both quantitative and qualitative data. Quantitative data, gathered through pretest and posttest along with the Metacognitive Awareness Listening Questionnaire, assessed the impact of MSI on students' listening skills and metacognitive strategy awareness. Qualitative insights were derived from informal, semi-structured interviews with EG participants, focusing on their experiences and perceptions of MSI. Findings revealed that postintervention, the EG showed significant improvements in listening skills and metacognitive strategy awareness compared to the CG. Specifically, the EG demonstrated notable advancements in planning and evaluation, directed attention, person knowledge, and problem-solving skills. However, both groups continued to rely heavily on mental translation, indicating a persistent dependence on their native language. The study underscores the potential of MSI in fostering learner autonomy and enhancing listening competencies in the Omani EFL context. It advocates for the integration of metacognitive strategies into the language curriculum, specialized teacher training, and the provision of accessible learning resources. The findings particularly highlight the importance of MSI in promoting autonomous learning behaviors, such as planning, monitoring, and evaluating one's own learning process. By enhancing metacognitive strategy awareness, MSI empowers students to take charge of their language learning, thereby increasing their self-efficacy and autonomy. The research suggests that targeted MSI can significantly contribute to the development of L2 learner autonomy in listening. It also recommends further investigation into MSI's long-term effects on promoting autonomy in other language skills and fostering overall learner autonomy in various educational contexts.