The integration of AI tools such as ChatGPT into language learning has attracted growing interest. With features like audio chat, these tools offer more opportunities for learners to practice speaking outside the classroom, which may contribute to building learners’ confidence and reduce foreign language anxiety (FLA) caused by limited exposure to the target language. This study examines the effectiveness of using ChatGPT as a language partner outside the classroom to enhance self-confidence and reduce FLA among 90 undergraduate students in Japan. Over a 15-week semester, participants engaged in three-minute audio conversations with ChatGPT. Pre- and post-intervention questionnaires were administered to assess learners’ perceptions of ChatGPT in language learning, as well as their anxiety and confidence levels. Results showed that while learners’ anxiety when interacting with ChatGPT decreased, their classroom anxiety and confidence levels remained unchanged. However, participants reported a significant improvement in attitudes toward AI in language learning, indicating increased awareness of how to use ChatGPT effectively and a willingness to explore more functions. These findings suggest that although ChatGPT has limited impact on reducing classroom anxiety and boosting confidence, learners’ positive attitudes and motivation indicate its potential as a valuable supplementary tool for speaking practice outside the classroom.