This study examines how followers’ social identity dimensions—cognitive, evaluative, and affective—affect their purchase intention for fashion products promoted by Instagram influencers. It also explores the mediating role of source credibility factors, including trustworthiness, expertise, and attractiveness, in strengthening this relationship. Targeting millennial females, a key fashion consumer group, the study applies social identity theory, source credibility theory, and influencer marketing literature to develop its conceptual framework. A quantitative, correlational approach was used, employing a self-administered questionnaire distributed via a convenience snowball sample of millennial females in Erbil, Kurdistan. Data from 421 respondents collected between were analyzed using SPSS AMOS version 24. Findings reveal that all social identity dimensions significantly influence purchase intention, and source credibility factors play a direct mediating role in this relationship. These insights offer practical implications for marketers and influencers, helping them understand the impact of followers’ social identity on purchasing behavior and refining influencer marketing strategies. This research expands influencer marketing literature by demonstrating the mediating effect of source credibility on the link between social identity and purchase intention. This research provides practical implications for enhancing millennial consumers’ purchase intentions by leveraging social identity mechanisms. The findings offer valuable insights for both social media influencers and brands seeking to employ influencer marketing strategies effectively in fashion promotion.
Al‐Abdallah et al. (2026) studied this question.