This study explores the impact of sociocultural theory-based instruction on enhancing L2 learners' writing skills including grammatical accuracy, coherence, cohesion, task response, and lexical resources for the IELTS. To this end, a cohort of 40 participants, spanning intermediate and advanced proficiency levels, was divided into experimental and control groups, each comprising 20 students. The research utilized the Oxford Placement Test to ensure a balanced distribution. Throughout the instructional period, learners actively participated in collaborative group activities and benefited from scaffolding techniques. The analysis of outcomes revealed the effectiveness of sociocultural strategies, leading to significant progress across different proficiency levels. While intermediate participants demonstrated marked improvements in task response, advanced learners exhibited heightened levels of coherence and cohesion in their writing. The findings indicate the paramount importance of employing scaffolding and collaborative methodologies to foster writing proficiency, particularly in the context of preparing for the IELTS. This research sheds light on the potential of sociocultural theory-based instruction to positively influence second language learners' writing abilities.