The current study investigated the effects of self-directed learning through implementing Artificial Intelligence (AI)-integrated smartphone speaking application (app) into an EFL classroom on undergraduate learners’ self-directed learning ability and speaking skills. A total of 76 students participated in this study and they were assigned to an experimental group 1 (n=26), an experimental group 2 (n=25) and a control group (n=25). Over a semester, the experimental group 1 engaged in self-directed learning through AI speaking apps and the experimental group 2 participated in AI speaking app-assisted language learning without self-directed learning while the control group participated in traditional speaking activities without the aid of AI speaking apps and self-directed learning. To collect data for this study, 1) a pre- and post-questionnaire on self-directed learning abilities and 2) a pre- and post-test on speaking skills were administered for each group. The results showed that self-directed learning through AI speaking app was effective in increasing the participants’ self-directed learning ability and speaking proficiency. However, the other two groups show no significant improvement in their self-directed learning abilities. This study suggests that self-directed learning through AI speaking apps offers many opportunities to practice speaking and is useful to develop students’ self-directed leaning abilities and speaking skills.