A Systematic Review of Theoretical Perspectives and Emerging Trends in Influencer Marketing

Abstract

The rapid growth and expansion of social media have shifted consumer expectations in marketing, which has moved spending from traditional advertising towards influencer marketing. Despite the high growth in this sector, many studies have focused on factors such as credibility, congruence, and parasocial responses, but very few studies have systematically analysed important theories and their implications. Hence, a comprehensive review of key theories and their association with influencer marketing is essential to provide authentic and structured research in the future. The literature review maps the theoretical perspectives applied in influencer marketing research and evaluates whether they are merely applied or authentically developed. A Systematic Literature review was conducted using PRISMA 2020. The search used appropriate keywords on the application Lens, covering Titles and Abstracts from English-language journal articles published between 2015 and 2026. The search returned 1063 records, of which 981 were screened, and 184 met the eligibility criteria. Each article was thoroughly studied for its theoretical perspective, Contextual characteristics, and profundity of theoretical application. The 184 studies utilised 63 different theories, but 145 of them, which is 79% of selected studies, did not modify their theoretical framework. Even though source credibility theory was repeatedly validated, it exhibited only a 10%, the lowest rate of theoretical development. Whereas the parasocial standpoint is widely and actively developed in many studies. Persuasion knowledge and the Stimulus-Organism-Response model showed no theoretical development, at 21%. Emerging trends include rapid growth towards virtual and AI-driven influencers, which is leading to the integration of human-computer interaction theories into the research area. The review differentiates between theoretical prevalence and theoretical productivity, uncovering that the most–cited perspective in the research is also one of the least developed. This also emphasises the proliferation of overlapping constructs that have to be consolidated. Marketers must treat influencer impacts as conditional rather than definite-specific to virtual influencers-and should prioritise expertise and trustworthiness over attractiveness when choosing endorsers.

Keywords: Influencer Marketing, Systematic Literature Review, Source Credibility Theories, Theoretical Framework, Virtual Influencers.