Abstract This study investigated the perceptions of high school EFL learners to the lexical instructional approach intervention in the contexts of learning vocabulary and grammar. Besides, an attempt was made to explore what difficulties the participants encountered during the experimentation. The data collected through the questionnaire were analyzed using a one-sample t-test, and the results showed that the estimated sample perception mean score was significantly higher than the hypothesized population perception mean score. This implies that EFL learners had positive perceptions towards the lexical instructional approach in the contexts of learning vocabulary and grammar. The data collected through interviews were analyzed qualitatively and the findings showed that students enjoyed and were interested in learning vocabulary and grammar through the lexical instructional approach. Students realized the importance of lexical chunks in learning vocabulary and grammar. In this regard, the interview results corroborated the results obtained from the questionnaire. Students encountered difficulties like lack of lexical awareness, lack of clear and adequate instructions on some activities, the lack of deliberate attention from some students during discussions, the lack of making some activities more interactive and engaging, and some classroom managerial problems. Finally, it was recommended that EFL teachers at high school should design their lexical approach-based activities systematically by considering their students’ interests, feelings, perceptions, levels, norms, cultures, and psychological setups.