This study presents evidence towards the existence of behavioural biases while analysing the impact of such biases on the investors’ investment performance in India, the USA, and the UK. Further, the study aims to investigate the moderating role of financial literacy on the relationship between behavioural biases and investment performance. It reveals that behavioural biases like affect heuristic, herding and status quo positively impact the investors’ investment performance amongst Indian investors whereas loss aversion, overconfidence, availability, and representativeness biases positively impact the investors’ investment performance amongst UK investors; and affect heuristic bias amongst USA investors. The findings divulge the negative impact of anchoring bias and mental accounting amongst Indian investors; availability bias, disposition effect, and overconfidence bias amongst USA investors; and affect heuristic and herding amongst UK investors. The study finds that a few of the behavioural biases impact investment performance positively, though less often. Hence investors should be cautious as these biases generally lead to irrational decision-making and might adversely influence the investors’ investment performance in the long run. The study further concludes that financial literacy significantly moderates the relationship between anchoring bias and individuals’ investment performance in India and affect heuristic in the USA. Interestingly, in the UK scenario, no significant moderating impact of financial literacy was found between any of the behavioral biases and investment performance.