The success of the banking sector depends heavily on the decision-making processes of customers, which are often influenced by various cognitive biases. This research study examines the impact of the anchoring and adjustment heuristic on the financial decision- making processes of customers in the banking sector, with a particular focus on the Tiruvallur district. The success of the banking sector depends to a large extent on customer decision- making, which can be influenced by various cognitive biases. The anchoring and adaptation heuristic, a well-established psychological principle, suggests that individuals tend to rely heavily on initial information when making decisions. The aim of this study is to investigate how this heuristic affects the financial decisions of customers in the banking services offered in Tiruvallur district.