The study investigates the influence of social media influencers (SMIs) on retail investors’ stock market decisions from a behavioural finance perspective. Utilising a quantitative, cross-sectional survey methodology, data were collected from 300 retail investors in India who actively follow financial influencers on platforms such as Instagram, LinkedIn, and X (formerly Twitter). The study examines the extent of reliance on influencers, the role of influencer credibility (IC), and the emotional triggers (ET) such as fear of missing out (FOMO) that shape investment behaviours. Structural equation modelling (SEM) via Amos and descriptive statistics were employed to analyse the data. Findings reveal that SMIs significantly impact retail investors’ decisions, with ET acting as mediating variables, while IC has a nuanced, sometimes inverse effect. The results highlight the behavioural biases that influence retail investors and underscore the growing importance of digital platforms in shaping financial literacy and investment strategies. The study contributes to the literature by linking behavioural finance with digital engagement, offering insights for improving investor awareness, curbing misinformation, and encouraging responsible financial communication on social media.