This study investigated the effect of the Metacognitive Intervention (MI) on the listening performance and metacognitive awareness of upper-intermediate learners of English as a Foreign Language (EFL) with low Working Memory Capacity (WMC). 136 male learners aged between 15 and 25 years formed the original pool of this study, and 94 were identified as upper-intermediate learners learning English at the English Language Institute (ELI) in Iran. They were further given the visual Digit Span Test (DST). Based on their scores and the median, 60 low-WMC learners were selected and randomly assigned to experimental (N = 30) and control (N = 30) groups. The experimental group received the MI through the pedagogical cycle for 10 sessions, whereas the control group followed a traditional approach. The participants in both groups were asked to take the International English Language Testing System (IELTS) listening tests and complete the Metacognitive Awareness Listening Questionnaire (MALQ) before and after the intervention. The results suggested that the experimental group had a higher gain with a moderate effect size in terms of listening performance than the control group. In addition, the MALQ revealed the significantly higher use of directed attention, mental translation, and person knowledge by the experimental group.