This study aimed to develop characteristics of the Genre-Based approach (GBA) via the Miro platform and to discover results on using this approach and the Gathering, Processing, Applying, and Self-Regulating (GPAS) process. The study employed experimental research using a true group pretest-posttest control group design with Grade 8 students divided into an experimental and a control group of 38 students per group by using cluster random sampling. The instruments were the lesson plans and the pre-and post-tests on English composition writing skills. The descriptive data analysis used to assess the results of the students' English composition writing skills were mean, standard deviation, and Repeated Measures MANOVA. The results from the study revealed that the researcher could develop a characteristic of GBA via the Miro platform for teaching because the statistical analysis results indicated that the experts approved the implementation of the lesson plans in this study using 5 levels of Likert Scale (mean = 4.72). Students who received teaching through the GBA via the Miro platform had significantly higher English composition writing skills than those taught through the GPAS process at the significant level of 0.05. These results confirm that using GBA via the Miro platform improved the students' composition writing skills.