This study investigates the Pakistani ESL school students' perceptions and their ESL teachers' practices of written corrective feedback in writing classes at Cambridge system schools in Karachi. This study employed a mixed-method approach to collect qualitative and quantitative data from the participants. Using the purposive sampling technique, a survey questionnaire was administered to 200 Grade IX and X ESL students of 5 Cambridge system schools. At the same time, semistructured interviews were conducted with 10 ESL O Level teachers from the same schools. The findings revealed that comprehensive corrective feedback was most frequently given by ESL school teachers to their students, followed by focused feedback and metalinguistic feedback in ESL classrooms. The students wanted their teachers to provide comprehensive and focused feedback on their written work. The qualitative results indicated that all teachers followed Cambridge assessment guidelines in terms of marking their students’ essays as they believed that this assessment covers every aspect of the language and helps students improve their writing skills. Overall, the results showed that students’ perceptions and teachers’ practices are generally