This research aims to improve the vocabulary knowledge of Thai EFL students by using audio-visual aids as instructional tools. Hopefully, this study serves as an initial foundation to develop students' vocabulary knowledge and benefit the pedagogical development in Thailand. Consequently, this research aimed to explore the effectiveness of audio-visual instruction in acquiring vocabulary knowledge, with a specific focus on the form-meaning links in Thai EFL primary school students. Additionally, this study investigated the students' perceptions of audio-visual input in enhancing vocabulary knowledge. The study included one experimental group consisting of 51 sixth-grade students. Two tests were used to measure the reception and production of form-meaning links (L2-to-L1 Translation Test and L1-to-L2 Translation Test). A questionnaire was used to examine the students' perceptions of the form-meaning links of vocabulary knowledge through audio-visual input. The results showed that the participants achieved higher scores on the reception and production tests of form-meaning links in the post-test than in the pre-test, revealing statistically significant differences. Furthermore, the students performed better on the reception test of the form-meaning link than on the production test in both time points, and the reception test was also higher in advancement than the production test. Finally, the reports demonstrated that the instructional intervention of form-meaning links of vocabulary knowledge (audio-visual input) positively benefits the development of students' vocabulary. The findings suggest that students' reception of vocabulary knowledge through audio-visual input is more advanced than their production of vocabulary knowledge. Moreover, the input of students' vocabulary knowledge contributes to acquiring and developing their knowledge.