Metacognitive awareness is widely associated with successful English language learning, yet empirical findings across listening, speaking, reading, and writing remain dispersed across different contexts, instruments, and instructional designs. This review synthesizes evidence on how metacognitive awareness contributes to four English language skills and how classroom and technology-mediated environments can support strategy instruction. A systematic literature review design was employed by searching Scopus, Web of Science, ERIC, ScienceDirect, SpringerLink, and Google Scholar for studies on metacognition, metacognitive strategy instruction, self-regulated learning, and English skill development. Ninety-eight records were identified; 61 focused on language learning, and 38 empirical studies were retained for skill-level synthesis after screening, eligibility checking, and quality appraisal. The evidence indicates that metacognitive awareness positively supports all four skills, but the strongest and most consistent support appears in reading and listening, where planning, monitoring, directed attention, problem solving, and evaluation directly regulate comprehension. Evidence for speaking and writing is also positive but more context-dependent because productive skills require learners to coordinate linguistic knowledge, task demands, anxiety, fluency, genre awareness, feedback, and revision. The review concludes that metacognitive awareness should be taught as an integrated, cross-skill competence rather than as isolated strategy training.