The rapid integration of Adaptive Learning Systems (ALS) and Artificial Intelligence (AI) in English as a Second Language (ESL) education holds tremendous promise, yet it is accompanied by significant challenges in its effective implementation. Moreover, ESL environments have become increasingly diverse in terms of learner demographics, linguistic backgrounds, institutional capacities, and cultural contexts. These complexities have further complicated the effective and efficient implementation of AI-based technologies in ESL contexts. In this study, a conceptual review approach was adopted to address this problem, where existing empirical literature and theoretical perspectives on the challenges and opportunities of implementing ALS and AI-based technologies in diverse ESL contexts have been synthesized. In this study, an interdisciplinary body of literature was consulted, and five major challenges in the effective implementation of AI-based technology in ESL contexts have been identified. These challenges include technological infrastructure gaps, linguistic and cultural biases in AI-based systems, teacher preparedness and professional development needs, learner diversity in terms of proficiency levels and learning styles, and issues of data privacy and academic integrity. Five major opportunities for effective implementation have been identified and discussed in this study, including personalized and adaptive learning, formative feedback, increased learner autonomy and motivation, inclusive education for special needs learners, and global applicability in ESL contexts. The paper also proposes a conceptual framework for a mixed-method approach to guide future research on ALS implementation. The study revealed that the efficacy of ALS and AI integration in ESL education does not solely depend on technological tools, as previously believed, but also on contextual factors such as educators’ preparedness, support from educational institutions, and the appropriateness of AI tools in relation to the sociolinguistic realities of ESL learners. This study ends with recommendations for researchers, educators, and policymakers who seek to effectively and responsibly integrate AI tools in language education.