Purpose: The study examines the effect of perceived authenticity and influencer credibility on customer trust in social media influencer marketing in Guyana. Specifically, it investigated how perceived authenticity of social media influencers affects customer trust, how influencer credibility shapes trust, and how these factors influence consumer engagement with promoted brands. The aim was to provide insights for designing effective influencer marketing strategies that foster trust and long-term brand loyalty in emerging digital markets.

Methodology/Design: A qualitative research design was adopted, using in-depth interviews with 25 active social media users in Guyana. Data were analyzed using thematic analysis. Trustworthiness, reliability, and validity were ensured through member checks, triangulation with prior studies, and consistent coding procedures. Findings were interpreted through the Source Credibility Theory and the Stimulus–Organism–Response (S–O–R) Theory to understand how authenticity and credibility influence internal trust responses and consumer behavior.

Findings: The results revealed that perceived authenticity strengthens customer trust through genuine communication, consistency, and emotional relatability, while influencer credibility enhances trust through expertise, honesty in sponsored content, and alignment with brand values. Both factors were found to significantly influence consumer engagement and willingness to follow influencer recommendations.

Implications: Marketers and influencers should prioritize authenticity and credibility when designing campaigns, select aligned influencers, and promote transparent communication to build trust and engagement.