This study aimed to improve students' vocabulary achievement by implementing the Memrise application among seventh-grade students at SMP Negeri 4 Kelapa. This study employed a quasi-experimental method with a non-equivalent control group design. The participants consisted of two classes, with 23 students in the experimental class and 23 students in the control class. Data were collected through vocabulary pre-tests and post-tests, as well as observation sheets to observe students' cooperation, participation, and conceptual understanding during the treatment. The data were analyzed using paired samples t-test and independent samples t-test. The results showed that the experimental class significantly improved in vocabulary achievement, with the mean score increasing from 43.69 to 68.29. The obtained t-value (11.849) was higher than the critical t-value (2.074), with a significance value of less than 0.001. The control class also showed significant improvement, with the mean score increasing from 50.14 to 62.81. The obtained t-value (8.049) was higher than the critical t-value (2.074), with a significance value of less than 0.001. However, the independent samples t-test showed no statistically significant difference between the two classes. Although the experimental class obtained a higher mean post-test score (68.29) than the control class (62.81), with a mean difference of 5.483, the obtained t-value (1.465) was lower than the critical t-value (2.015), and the significance value (0.150) was greater than 0.05. This non-significant result may be related to the relatively small sample size and the variability of students' scores, which may have reduced the ability to detect the difference between the groups. Therefore, the findings indicate that students' vocabulary achievement significantly improved in the experimental class, although there was no statistically significant difference between the experimental and control classes.