INFLUENCE OF SOCIAL MEDIA INFLUENCER MARKETING ON CONSUMER PURCHASE BEHAVIOUR AMONG YOUTH IN NAIROBI COUNTY, KENYA

Abstract

Social media influencer marketing has become a dominant digital strategy shaping consumer attitudes and purchase behaviour, particularly among youth who rely heavily on social platforms for product discovery and recommendations. Despite increasing investment in influencer-based campaigns by SMEs and other businesses in Nairobi County, empirical evidence establishing the key influencer-related factors that determine purchase behaviour remains limited in the Kenyan context. This study examines the influence of social media influencer marketing on consumer purchase behaviour among youth in Nairobi County, Kenya. Specifically, the study assesses the effect of influencer credibility, influencer–brand congruence, content quality, and engagement intensity on consumer purchase behaviour. The study is anchored on Source Credibility Theory which posits that persuasion is enhanced when message sources are perceived as trustworthy, expert, and credible. A descriptive cross-sectional survey design is proposed, targeting youth social media users aged 18–35 years in Nairobi County. Data was collected using structured questionnaires and analysed using descriptive statistics, Pearson correlation analysis, and multiple regression modelling. Hypothetical results indicate that influencer credibility and engagement intensity significantly predict purchase behaviour, while content quality and influencer–brand congruence show moderate positive effects. The study concludes that influencer marketing effectiveness is driven more by credibility and interactive engagement than by entertainment value alone. The study recommends that SMEs prioritize credible influencers and engagement-focused influencer strategies to achieve conversion-oriented campaign outcomes.

Keywords: influencer marketing, credibility, engagement, brand congruence, content quality, purchase behaviour, Nairobi County