This action research aimed to investigate the efficacy of written corrective feedback as a learning approach to improve the patterns of development in English for Academic Purposes (EAP) among Grade 11 General Academic Strand (GAS) students. Specifically, the study sought to determine how written corrections and guided revisions influenced students’ ability to organize ideas using narration, description, comparison, cause-and-effect, and other patterns of development in academic writing. The participants were Grade 11 GAS students who were given writing tasks followed by peer-provided corrective feedback. Data were gathered through pre-test and post-test writing outputs, classroom observations, and students’ reflective journals. Findings revealed that students demonstrated notable improvement in clarity, coherence, and accuracy of their written outputs after receiving consistent feedback. Moreover, the intervention enhanced learners’ awareness of their common writing errors and encouraged them to adopt better writing strategies. The study concludes that written corrective feedback is an effective approach in strengthening Grade 11 GAS students’ academic writing skills, particularly in mastering patterns of development in English for Academic Purposes.