The present study aims to investigate the effect that Quizlet vocabulary learning has in terms of improving the vocabulary of Korean language learners. To this end, this study first examined the theoretical background by analyzing previous studies on computer-based vocabulary learning, mobile-based vocabulary learning, and Quizlet vocabulary learning; it then compared the satisfaction level of learners who used the Quizlet vocabulary learning method with that of learners who used conventional methods of vocabulary learning. In addition, this study tested and analyzed the effectiveness of vocabulary learning using computers (or mobile apps) in improving learners’ vocabulary. An instructor delivered the same content, using the same method, to 28 international undergraduate students, who made up the experiment and control groups. To confirm the homogeneity of these two groups, a Korean vocabulary proficiency test was performed as a pre-test. The result of a t-test returned a significance of p<.05 and confirmed that there was no statistically significant difference between the two groups. The experiment group utilized Quizlet to learn vocabulary, while the control group used conventional methods of vocabulary learning. Eight rounds of quizzes were then administered to confirm the learners’ performance levels. After the experiment, this study compared the performance levels of the two groups, with the following results: the experiment group achieved higher scores than the control group over all eight rounds of quizzes. Moreover, all the learners in the experiment group expressed a high level of satisfaction and interest in vocabulary learning using Quizlet, which utilizes computers or mobile apps. The present study verified the effectiveness of Quizlet vocabulary learning, which moves beyond conventional vocabulary learning methods, and confirmed the necessity to provide this type of vocabulary learning in language education. (Pyeongtaek University)