Diagnosing an issue followed by creativity and innovation are three key factors for a successful English teaching. English writing has always been a challenge for EFL learners to master. Moreover, in this modernized era, while online teaching has been attracting more attention, there proved to be some difficulties for the instructors to adopt it. Hence, to resolve the issues, the following inquiry examines the influence of WhatsApp group collaboration integrated with instructional video clips on Iranian intermediate EFL learners’ writing skill and their writing accuracy in online classes. In addition, the perception of the students towards this technique of teaching writing was also investigated. Accordingly, a mixed-methods design study with the employment of a pre-test, post-test, and a questionnaire was conducted. A total of 38 screened Iranian intermediate EFL learners were divided into the experimental (N= 19) and the control (N=19) groups. Both groups were taught in online classes and had the same book and syllabus. The only difference was that the experimental group was treated using additional instructional video clips which were shown in the class and wrote their writings task collaboratively in WhatsApp; yet the control group wrote their assignments individually and was taught conventionally. The data was analyzed utilizing descriptive statistics and independent and sample t-tests. The results demonstrated the improvement of both groups after the course; in the post-test scores, the experimental group significantly outperformed the control group in both the overall writing performance and writing accuracy. Moreover, the post-test questionnaire results revealed general satisfaction of the experimental group. The research findings have pedagogical implications for teachers to adopt this technique to advance teaching writing to EFL learners in online modality.