Vocabulary Learning Strategies (VLSs) are widely implemented in the learning of English as a second language (ESL). Hence, VLSs are helpful in aiding learners to develop their vocabulary effectively, not only in the classroom but also out-of-classroom, according to the learners' needs. This study aims to investigate the use of vocabulary learning strategies in incidental learning among high and low proficiency Year 6 ESL learners. The sample of this study are 30 Year 6 ESL learners from a primary government school in Bandar Baru Bangi. A mixed method was employed, and purposive sampling was used for this study. Data was collected through a 26-item questionnaire based on Schmitt’s Taxonomy of Vocabulary Learning Strategies Questionnaire (VLSQ) and semi-structured interviews. The findings indicate that high proficiency learners “watch English media” the most and the “use of flashcards” as the least favoured. In contrast, low proficiency learners prefer “asking parents or family members for the meaning of words” and “reading English newspaper, magazines and books” the least. Although no significant differences were found in overall strategy use between high and low proficiency groups, metacognitive strategies were employed significantly more by high proficiency learners. Both high and low proficiency Year 6 ESL learners also perceive technology tools and multimedia as effective for incidental learning by using YouTube, social media platform, online games, use of sub-titles and digital dictionaries. Further research on a larger scale among primary school learners is recommended to inform teachers about the application of vocabulary learning strategies, particularly in incidental learning.