The rapid growth of Financial Technology (FinTech) has transformed the global financial services landscape by offering innovative, accessible, and customer-centric solutions. FinTech encompasses a wide range of services, including digital payments, mobile banking, peer-to-peer lending, robo-advisory services, blockchain-based financial products, and digital insurance. While technological innovation has enhanced convenience, speed, and financial inclusion, customer adoption and long-term usage largely depend on trust. Trust serves as a critical determinant of customer behaviour, influencing perceptions of security, reliability, transparency, and service quality. In digital financial environments where face-to-face interactions are limited, trust becomes even more important because customers must rely on technological systems, data protection mechanisms, and organizational integrity. This chapter explores the relationship between customer behaviour and trust in FinTech. It examines the factors influencing customer adoption, usage intentions, satisfaction, loyalty, and continued engagement with FinTech platforms. The chapter discusses key theoretical foundations, determinants of customer behaviour, dimensions of trust, challenges in building trust, and strategies employed by FinTech firms to enhance customer confidence. Additionally, it highlights the impact of emerging technologies such as artificial intelligence, blockchain, and big data analytics on customer perceptions and trust formation. The chapter concludes by emphasizing the need for a customer-centric approach that prioritizes transparency, security, regulatory compliance, and ethical technology use to foster sustainable growth in the FinTech sector.