This research focuses on addressing the challenges in writing skills faced by preparatory school students, particularly in the context of grammar, mechanics, and overall writing abilities. The study is driven by the observed weaknesses in students' writing performance, identified through a pilot study that revealed issues such as punctuation, spelling, sentence formation, word expressions and grammar. The traditional teaching methods and the predominant use of the Arabic language in English classes were identified as contributing factors to these challenges. The researcher proposes the use of the online Think-Pair-Share (TPS) cooperative learning strategy as an innovative approach to enhance students' writing skills. While previous studies have recognized the positive impact of cooperative learning strategies, this research specifically focuses on the online implementation of the Think-Pair-Share strategy. The literature review asserts the benefits of cooperative learning, emphasizing active participation, positive attitudes toward writing, increased importance of feedback, stress reduction, and the promotion of higher-order thinking and communication skills. Additionally, the research aligns with the contemporary trend of utilizing online learning, highlighting advantages such as flexibility, immediate feedback, better retention, access to up-to-date content, and suitability for 21st-century learning environments. The research aims to investigate the effects of online Think-Pair-Share strategy in improving the writing skills in EFL preparatory school students. The significance of this research lies in its potential to contribute to the improvement of writing skills among preparatory school students, fostering cooperative learning, and integrating online strategies that align with contemporary educational needs.