Moodle-based blended learning is increasingly recognized as an effective strategy to address challenges in traditional English instruction. This study investigates its impact on English proficiency among Grade 10 students at Chu Van An High School in Thanh Hoa, focusing on two objectives: (1) exploring students’ perceptions of Moodle’s usability and (2) evaluating the effectiveness of Moodle-based blended learning compared to traditional methods. Using a mixed-methods approach, the study involved 80 students divided into two groups: 40 received blended instruction via Moodle, while 40 experienced traditional face-to-face teaching over six weeks. Results showed that students in the blended learning environment had significantly better English proficiency, especially in reading, listening, and writing. Additionally, they reported increased motivation, greater autonomy, and positive attitudes toward learning English.