The rapid proliferation of artificial intelligence (AI) has created new affordances for second language acquisition (SLA), particularly in adult education. However, empirical evidence regarding the efficacy of AI-integrated instruction for adult learners facing unique challenges such as time constraints and foreign language anxiety (FLA) remains lacking. This study employed an explanatory sequential mixed-methods design to investigate the impact of AI-integrated pedagogy on English proficiency and anxiety levels. The sample consisted of 72 adult English as a foreign language (EFL) learners (N=72) divided into an experimental group (n=36) utilizing generative AI tools (e.g., chatbots, voice assistants) and a control group (n=36) following a traditional textbook-based curriculum over a 16-week period. Quantitative analysis revealed that compared with the control group, the experimental group achieved statistically significant gains in overall proficiency (p < .001), particularly in speaking and writing. Furthermore, the AI group demonstrated a drastic reduction in foreign language anxiety levels. The qualitative findings from the semistructured interviews indicated that the learners perceived the AI as a “nonjudgmental” practice partner that provided immediate feedback and enhanced learner autonomy. These results suggest that AI integration offers a scalable solution for overcoming affective and logistical barriers in adult language education.