Web-based games can be an alternative learning media for students to improve their vocabulary mastery in reading. Nevertheless, few studies look at how web-based games can be used as a teaching tool to help junior high school students improve their vocabulary, especially in the context of reading. The main objective of this research is to know the differences between the improvement of vocabulary mastery of 7th grade students at a junior high school in Indonesia who use the web-based vocabulary game "WordWall" compared to those who do not. The study employed a quasi-experimental design by administering both pre-test and post-test as instruments for data collection. Furthermore, as research participants, there were two classes from one of the junior high schools in Surabaya: 7E as the experimental group (N=31), and 7F as the control group (N= 31). The findings of this research showed that the significance value <0.05 was achieved (0.00), which indicates that there is a significant difference in the results of learning vocabulary between the experimental group and the control group. It can be concluded that using web-based games has a significant impact on students' improvement in vocabulary mastery in reading than those who do not.