Behavioural finance challenges the rationality assumption central to classical finance, demonstrating systematic deviations driven by cognitive, emotional, and social biases. This study investigates how behavioural biases influence retail investors’ decision-making, with a focus on overconfidence, loss aversion, herd behaviour, confirmation bias, and emotional trading. A purposive sample of 30 retail investors was selected based on experience and active trading during volatile market periods. Semi-structured interviews were conducted and analysed using thematic analysis (Braun & Clarke, 2006), with rigor ensured through member checking, peer debriefing, and triangulation. Five primary themes emerged: overconfidence, herd behaviour, loss aversion, confirmation bias, and emotional trading during volatility. Sub-themes such as digital amplification, regret minimization, skill attribution, and selective information processing were identified. The study develops a conceptual framework linking cognitive bias, emotional response, and digital influence, offering insights into behavioural finance theory and practical implications for financial advisors, fintech platform design, and policy interventions.