The objective of this study is to examine the impact of inquiry-based writing instruction on the development of academic writing skills in English as a Second Language (ESL) and English as a Foreign Language (EFL) learners. This research addresses two key questions: What are the outcomes of implementing inquiry-based writing instruction methods? How can inquiry-based writing instruction be effectively integrated into academic writing instruction to enhance learners' writing abilities? This study employed a critical literature review following Snyder’s (2019) procedures, in which the data were retrieved from scientific databases, critically evaluated based on methodological rigor, data quality, and source credibility, and synthesized to identify key themes, similarities, differences, contradictions, and gaps in existing research. The analysis of previous studies and other related sources indicates that inquiry-based writing instruction is a crucial factor in developing English academic writing competencies in ESL/EFL learners, particularly effective in developing critical thinking skills, which is a crucial aspect of academic writing. It also addresses the shortcomings of existing academic writing teaching and learning methods and results in improved quality of task accomplishment, coherence, cohesion, lexical resources, grammatical range, and accuracy of academic writing. Further analysis also revealed that the development of critical thinking is achieved through an interrelated process such as engagement, exploration, explanation, elaboration, assessment, and reflection.