In the rapidly evolving landscape of financial technology (FinTech), the seamless integration of various systems has emerged as a critical factor in optimizing transaction volumes and enhancing overall operational efficiency. This review explores the key strategies and technological innovations that drive successful systems integration within FinTech platforms, focusing on the implications for transaction scalability, security, and user experience. With the increasing complexity of financial ecosystems, FinTech companies face the challenge of integrating disparate systems, including payment gateways, data analytics platforms, customer relationship management (CRM) tools, and regulatory compliance modules. Effective integration not only ensures the smooth flow of information across these systems but also enhances transaction processing capabilities, enabling FinTech companies to handle larger transaction volumes with minimal latency and errors. This study highlights the role of advanced integration technologies, such as Application Programming Interfaces (APIs), microservices architecture, and cloud computing, in facilitating real-time data exchange and processing across platforms. Additionally, the integration of machine learning algorithms and artificial intelligence (AI) enhances predictive analytics and decision-making processes, further boosting transaction efficiency and scalability. The review also discusses the importance of maintaining robust security protocols during systems integration to protect against cyber threats and ensure compliance with financial regulations. By adopting a holistic approach to systems integration, FinTech companies can achieve a higher level of operational agility, thereby meeting the growing demands of digital consumers and capitalizing on the expanding digital economy. Keywords: FinTech, Systems Integration, Transaction Volumes, APIS, Microservices Architecture, Cloud Computing, Machine Learning, Artificial Intelligence, Cybersecurity, Operational Efficiency.