Artificial Intelligence (AI) has initiated a new era in education with significant potential to revolutionize teaching and learning. ChatGPT has attracted scholars' interest in exploring its beneficial aspects and constraints for enhancing teaching methods and learning experiences. This systematic review aims to investigate the advantages and challenges of ChatGPT for EFL/ESL writing. The data was gathered from three databases, namely Web of Science, Science Direct, and ERIC, between November 2022 and January 2024. A total of 182 publications were gathered using precise keywords, and the 15 most pertinent articles were selected following the PRISMA flowchart. Findings show that ChatGPT can enhance writing efficiency and creativity, improve writing proficiency, and personalize learning experiences. It can also reduce teachers' workload by offering automated evaluation, feedback, and support for revision. The results also show that despite its potential advantages for both instructors and learners, it presents some challenges, such as overreliance, decreased motivation, learning loss, identifying errors at the deep level of the language, offering inconsistent and complex feedback, and issues with academic integrity and originality. The detailed findings and their implications for practice and policy are discussed.