Advances in mobile technology have transformed language education, enabling innovative approaches like mobile-assisted blended and backward design learning. However, the combined effects of these instructional models with intensive versus extensive reading remain underexplored. As such, this quasi-experimental study compared the effects of mobile-assisted blended learning and backward design, integrated with intensive and extensive reading, on the reading comprehension of Iranian intermediate-level learners of EFL. Eighty participants were randomly assigned to four experimental groups: blended intensive, blended extensive, backward intensive, and backward extensive reading. All groups received intervention via Telegram, followed by pre- and post-testing using parallel TOEFL reading comprehension tests. Additionally, semi-structured interviews were conducted to explore their perceptions of learning experiences. One-way ANOVA revealed significant differences among the groups. The backward extensive reading group significantly outperformed all other groups. Furthermore, the blended extensive group outperformed the blended intensive group. However, no significant difference was found between the backward intensive and blended intensive groups. The qualitative analysis of the interviews revealed that learners in the backward extensive group placed a great emphasis on pre-class preparation, which fostered confidence and readiness for in-class collaborative activities. Also, the learners in both of the extensive reading groups reported that they enjoyed the course more than the students in the intensive groups. The accessibility and ease of use of the Telegram platform were also lauded across all groups for promoting consistent engagement. The findings suggest that mobile-assisted extensive reading within a backward design framework is highly effective for enhancing Foreign language (FL) reading comprehension.