The article explores how cognitive biases affect the negotiation process in international business-to-business (B2B) interactions. The aim of the study is to identify how cognitive biases and principles influence the effectiveness of negotiations in the international business environment. The study employed general scientific methods of cognition, including analysis, synthesis, induction, deduction, comparison and generalization. The findings indicate that cognitive biases play a significant role in decision-making during international B2B negotiations. They shape the subjective perception of information, influence risk assessment approaches, and affect the choice of interaction strategies between parties. Among the most influential biases are confirmation bias, the blind spot bias, and the availability heuristic – all of which operate on a subconscious level, leading to distorted assessments of counterparties, deeper cross-cultural barriers, and reduced overall communication efficiency. Understanding the presence and mechanisms of these biases can improve the quality of managerial decisions and enable more accurate predictions of partner behavior in a complex global context. The study also reveals that three cognitive principles play a crucial role in international B2B negotiations: authority, social proof, and reciprocity. The principle of authority helps build trust by appealing to expert opinion. Social proof reduces perceived risk by showing that certain actions are supported by other market participants. However, the principle of reciprocity proves to be the most effective for establishing long-term partnerships, as it is based on a moral obligation to return goodwill. In the international context, gestures such as offering free advice or symbolic gifts are particularly effective - they create cognitive pressure while simultaneously serving as powerful tools for building trust. Overall, cognitive biases can either enhance negotiation effectiveness or become sources of risk if left unchecked. Practical value of the study lies in the potential to improve negotiation strategies by consciously leveraging and mitigating cognitive biases in the international business environment.