Despite widespread theoretical acceptance of the intelligibility principle in second language pronunciation pedagogy, a significant gap persists between research recommendations and classroom implementation, particularly in English as a Foreign Language contexts. This mixed-methods study investigated the effectiveness of intelligibility-oriented pronunciation instruction among 84 intermediate-level Iranian EFL learners at Islamic Azad University, South Tehran Branch. Participants were randomly assigned to experimental and control groups, with the experimental group receiving 16 weeks of explicit instruction on suprasegmental features—stress, rhythm, and intonation—integrated with perceptual training and communicative practice. Quantitative data were collected through pre-test and post-test measures of intelligibility and comprehensibility, while qualitative data were gathered through semi-structured interviews. Results revealed significant improvements in the experimental group's intelligibility scores (t = 6.82, p < .001, d = 1.24), with suprasegmental accuracy accounting for 58% of variance in comprehensibility ratings. Findings underscore the critical role of explicit suprasegmental instruction and perceptual training in enhancing L2 phonological learning and provide empirical support for integrating intelligibility-oriented approaches in Iranian EFL contexts