Does Influencer Expertise Matter Most? A PLS-SEM Investigation of TikTok Influencer Attributes, Brand Trust, and Purchase Intention among Generation Z Consumers in Vietnam

The rapid proliferation of TikTok commerce has fundamentally transformed how Generation Z consumers evaluate and trust influencers, yet the existing body of research offers limited insight into which influencer attributes drive brand trust within short-form, algorithm-driven environments. This study addresses this gap by examining whether traditional credibility cues—including popularity, expertise, credibility, and informative value—retain their predictive power for brand trust and purchase intention among Vietnamese Gen Z consumers. Grounded in Source Credibility Theory and the Advertising Value Model, this research develops and empirically tests a structural model incorporating four influencer attributes as antecedents of brand trust, which in turn predicts purchase intention. Primary data were collected through an online survey administered to 142 TikTok users in Ho Chi Minh City and subsequently analyzed using partial least squares structural equation modeling (PLS-SEM). The findings reveal that only influencer expertise significantly enhances brand trust, while popularity credibility, and informative value do not exhibit statistically significant effects. Brand trust, in turn, strongly predicts purchase intention. These findings indicate a paradigmatic shift toward competence-based evaluation in short-video platforms, challenging conventional assumptions derived from Source Credibility Theory and highlighting the diminishing relevance of surface-level cues in algorithm-mediated environments. This study contributes to the digital marketing literature by elucidating expertise-centric trust formation mechanisms and offers actionable implications for brands seeking to optimize influencer marketing strategies targeting Gen Z consumers in emerging Southeast Asian markets.