Developing writing skills is an important objective in English language learning because it enables students to express ideas, organize information, and communicate effectively through written texts. Nevertheless, many junior high school students encounter difficulties in writing narrative texts, particularly in generating ideas, arranging story events logically, and constructing complete narrative structures. This study investigated the effectiveness of Picture Series Media in improving the narrative writing ability of eighth-grade students at SMPN 4 Monta. The research adopted a quantitative method using a true experimental pre-test–post-test control group design. 41 students participated in the study, comprising 21 students in the experimental group and 20 students in the control group. Students' writing ability was assessed through narrative writing tests, and the data were analyzed using descriptive statistics together with the Shapiro–Wilk normality test, Levene's homogeneity test, paired samples t-test, and independent samples t-test. The analysis revealed that students who learned through Picture Series Media achieved higher narrative writing scores than those who received conventional instruction. Greater improvement was also observed in students' ability to develop the orientation, complication, and resolution of narrative texts. The independent samples t-test showed a significant difference between the two groups (t = 3.604, p < 0.001). These findings demonstrate that Picture Series Media is an effective instructional medium for improving students' narrative writing ability.