The present research investigates the effect of self-regulatory strategy instruction on Iranian EFL learners' metadiscoursal writing abilities. To this purpose, 50 Iranian EFL intermediate learners were all native speakers of the Persian language learning the English language in an institute were selected via convenience random sampling. Self-regulated Strategies Intervention and Metadiscoursal writing pretest and post-test were the research instruments employed to collect the data. Because of the circumstance of COVID-19, the instructor made a new WhatsApp group apart from the virtual group, namely Adobe Connect, to make contact with the students. The learners were required to take a metadiscoursal writing pretest. After passing six sessions, intervention through self-regulated strategies was taught, and the participants were required to follow the guidelines. The instructor checked every single learner's progress. Ultimately, they took a post-test. The findings revealed that the self-regulatory strategy significantly impacted Iranian EFL learners' metadiscoursal writing skills. In conclusion, the results indicated that it could be suitable for teachers to gain more information regarding the self-regulated strategy and utilize it, where necessary, for its positive results.