Metacognition plays a crucial role in language learning, enabling learners to reflect on and adjust their strategies for more effective learning, particularly when reviewing for quizzes and exams. Technology can be a powerful aid in this context. This study examines the extent to which review-focused cognitive strategies, delivered using an online blended learning tool, support the metacognition of university-level English learners in Japan. Thirty learners in total participated in the study. They were enrolled in the teacher-researcher's thirty-week, first-year, compulsory English reading and writing course. The instruments employed were two learner reports, an end-of-course questionnaire, learner records from the tool's database, and the teacher-researcher's research journal. Findings indicated that: (1) the tool supported learners' metacognition by raising their awareness of gaps in their English-related linguistic knowledge, aiding their strategic planning for upcoming quizzes and exams, and providing opportunities for learners to explore new cognitive strategies; (2) many learners used their metacognitive skills to maximize their effort and select and use cognitive strategies with intentionality; and (3) the overall assignment had a positive impact on the test-anxiety of many learners. These findings confirm the potential of blended learning tools for fostering out-of-class review behaviors and learners' metacognitive development. Pedagogical implications are discussed and suggestions for future research are provided.