This study conducts a comprehensive analysis of the landscape of investor sentiment research and constructs an agenda for future research. Utilising systematic literature reviews and bibliometric analysis, we examine 1,274 high-quality publications from the Web of Science database (1991–2023), employing HistCite and R bibliometric packages for bibliometric mapping and citation analyses. We identify three main themes: the effect of investor sentiment on asset returns, financial risks, and market anomalies. Additionally, we explore emerging research areas such as the relationship between sentiment and uncertainties, alternative investments, market globalisation, and new sentiment measures, broadening the scope and depth of behavioural finance research.