Artificial intelligence (AI) tools are increasingly used in English as a Foreign Language (EFL) education to support personalized learning and learner autonomy. This study investigates how AI tools influence autonomous learning behaviors among EFL students at Dong An Polytechnic (DAP) in Vietnam. Using a mixed-methods design, data were collected from 112 students through a questionnaire and follow-up semi-structured interviews. The findings show that frequent users of AI tools including Grammarly, ChatGPT, ELSA Speak, and Duolingo demonstrated higher levels of goal-setting, self-monitoring, self-evaluation, and learning motivation. Students reported positive perceptions of AI, valuing its convenience, immediate feedback, and ability to build confidence. However, challenges such as digital literacy limitations, reliance on AI suggestions, and concerns regarding academic integrity were identified. The results highlight the need for structured AI integration, responsible use guidelines, and institutional support. The study provides implications for teachers, curriculum designers, and policymakers and suggests directions for future research.