This study examined the effectiveness of using visual vocabulary application on Iranian EFL learners’ vocabulary knowledge. To this end, 42 intermediated EFL learners were selected as the participants of the study and divided into two groups of 21- experimental and control. Then, the groups took a pre-test of vocabulary. After that, the experimental group received the treatment thorough visual vocabulary application. On the other hand, the control group participants were taught vocabulary items traditionally. After teaching all vocabulary items, a vocabulary post-test was administered to the participants of both groups to measure the effect of the treatment on their vocabulary development. The results of paired samples t-test and independent samples t-test indicated that that the experimental group outperformed the control group on the post-test. The results also indicated that there was a significant difference between the post-tests of both groups in favor of the experimental group. Finally, implications arising from the findings and suggestions for further research were explained.