This study investigated the effect of the flipped learning model on first-year EFL students' grammar achievement and their perceptions of the approach. A quasi-experimental design was employed, involving freshman students from the Natural Science stream, who were divided into control (N = 49) and experimental (N = 46) groups. Over six weeks, while the experimental group received the course with the flipped learning model, the control group received the course using conventional methods. Pre- and post-tests and a questionnaire were used to collect data about the students' grammar achievement and their perceptions, respectively. The pre-test, post-test, and questionnaire results from a reliability analysis using Cronbach's alpha were 0.85, 0.84, and 0.837, respectively. The results revealed statistically significant improvements in grammar achievement and their perceptions of the model. However, no correlation was found between the two variables. Based on these findings, the study concluded that flipped learning positively impacted grammar achievement and was well-perceived by the students. Finally, conclusions and educational implications are discussed in light of the findings.