Vocabulary learning is one of the most challenging aspects of learning a foreign language, especially vocabulary retention at the beginner level. There are currently a number of lexical instruction strategies available, but their use in the Vietnamese EFL context is still limited. Therefore, the appropriateness and efficacy of incorporating word games into English lexical instruction at a middle school in South Vietnam were investigated in this report. Mixed method research was conducted on two classes in grade 7 for eight weeks in order to measure the efficacy of using games in the selected school. Two classes (experimental and control) with 64 students whose English proficiency is more or less the same based on preliminary test scores learned the same vocabulary lessons-the formerly used games to learn vocabulary, while the latter used the conventional approach. Pretests, posttests, questionnaires, and interviews were used to collect the data. The experimental group's increase in vocabulary retention was statistically better than the other in the post-test findings after eight weeks of treatment. Furthermore, qualitative analysis revealed that the experimental group participants found word games to be inspiring, fun, and efficient. This paper concludes that using games to teach vocabulary has proven to be a viable method for English teaching and learning in middle school EFL classes. Learners had more chances to be exposed to the target language in a fun and comfortable learning atmosphere by playing word games and improved their ability to acquire and maintain vocabulary.