Research revealing the educational values of gamification in English as a Foreign Language (EFL) education has proliferated in the last decade. However, these studies have yielded inconclusive findings of its efficacy. Furthermore, studies on the use of mobile devices have also reported some potential pitfalls when being used for educational purposes. This quasi-experimental study thus set out 1) to evaluate the effectiveness of gamified vocabulary learning in a mobile-assisted language environment on Indonesian adult EFL learners’ vocabulary learning outcomes, and 2) to explore their perceptions of its benefits. Two classes comprising 74 first-year students taking a General English course at a state university in Indonesia were selected as the participants in this study and later randomly assigned to experimental and control groups. In addition to pre- and post-tests, online questionnaires were employed to collect data, which were analyzed using the SPSS 20 package. The main findings indicated that the students in the experimental group outperformed their counterparts in the control group. Furthermore, they confirmed the benefits of mobile-assisted gamification for their vocabulary learning in three aspects: learning outcomes, enjoyment, and motivation. In conclusion, these findings confirm the legitimacy of gamification and mobile-assisted language learning to scaffold EFL education
