<p>Understanding learner engagement with peer feedback in socially-embedded contexts has been wellnoted, particularly regarding the importance of contextual factors including interpersonal factors like peer familiarity. However, the specific role of peer familiarity remains underexplored from an interpersonal perspective in authentic pedagogical settings. To get a more in-depth comprehension, this study conducted a quasi-experiment in a real online teaching environment. 154 university students participated in a peer feedback activity set in a 10-week Micro-video Production course, and the students were then divided into familiar and unfamiliar groups. A combination of statistical analysis, epistemic network analysis (ENA), and cluster analysis was used to handle both qualitative and quantitative data. The results suggested that the familiar groups usually showed higher behavioral engagement, more critical cognitive interactions, more dynamic affective exchanges, and more positive learner profiles. Moreover, ENA further revealed stronger interpersonal connections (e.g., <i>personal opinion-suggestion</i> and <i>personal opinion-others</i>) in familiar groups. The findings indicate that peer familiarity is notably associated with learners’ behavioral, cognitive and affective engagement with peer feedback. The study underscores the importance of fostering interpersonal familiarity and considering interpersonal factors in designing peer feedback activities to enhance learning engagement and outcomes.</p>