Virtual advocates for sustainability: How influencer type and message congruence shape consumer responses in emerging markets

As digital marketing evolves and sustainability communication gains urgency globally, virtual influencers emerge as potential advocates for eco-friendly consumption. This study investigates the impact of influencer type (human vs. virtual) and message congruence on consumer responses to sustainable fashion promotions in Egypt, representing emerging market perspectives that are often underrepresented in sustainability research. Using a 2 × 2 experimental design with 311 Gen Z participants, we applied Source Credibility Theory and the Match-up Hypothesis to understand these dynamics. Results reveal that credibility significantly influences both engagement (f2 = 0.383) and purchase intentions (f2 = 0.302) for sustainable fashion, with trustworthiness emerging as the dominant credibility dimension. Human influencers outperformed virtual influencers, particularly in congruent messaging conditions, thereby challenging assumptions about the effectiveness of virtual influencers in sustainability contexts. These findings advance influencer marketing theory by demonstrating context-dependent credibility mechanisms and provide actionable insights for brands expanding sustainability messaging into emerging markets where environmental awareness is developing.